Let's start with some useful links:
 
 

General
 

• Language  Not surprisingly, the German people speak the German language.  This language is similar to Dutch, Swedish, and Danish.  It is also an ancestor of the English language.   Like in many European countries, many, if not most, German children start studying English at a young age.  So, a visitor should not have too much trouble finding an English speaker while in Germany, to help with your shopping, tourism, travel, etc.  Right after I got married in 1998, my wife came to live with me in Bonn for a few weeks before we moved back to the US.  She spoke no German, but didn't have too many problems getting around in the city.  The Germans are willing to speak English with you.  That said, I suggest you try to learn at least a little German before you go.  At the very least, learn to say you don't speak German (Ich spreche kein deutsch) and to ask if one speaks English (Sprechen Sie Englisch?).  This is politeness if nothing else.  Besides, if you can take the time and learn a little German, you will get more out of your experience, in my opinion.
• Beer  Let's face it, this is a very important subject for those visiting or living in Germany.  Bier aus Deutschland is a nice website dedicated to beer, available in English and German.  A lot of exported beers advertise in the US as being brewed according to the Reinheitsgebot of 1511.  All German beer is brewed according to this, so this is kind of meaningless.  Beer making is an art form in Germany, and it varies greatly from region to region; beer from Cologne is very different from Munich beer.  Those are the two I know the best, so I'll only talk about those.
• Kölsch  This is the beer (and dialect) peculiar to the region surrounding the city of Cologne.  This region includes Bonn.  Kölsh beer is my favorite.  Unfortunately, none of the brewers appear to export their product so I haven't had any since I left.  Of all the people I've introduced Kölsch to, only one didn't absolutely love it.  He liked it, but preferred a stronger, Irish beer.  My favorite brand is Dom, but Mühlen is also good.  I recommend you avoid Küppers.  Though this is, I believe, the most popular and least expensive, it isn't very good.
• Munich  The Bavarians prefer a wheat beer.  Several brewers do export their product, and it can be found all over Europe, as well as here in the US.  It isn't cheap, but quite good.  The most common brand is Paulaner, which I can get here in the US.  I can't argue against it.  I prefer the Franziskaner brand, which is also available here.  The Bavarians server their been in liter (quart for those non-metric readers) sized glasses called maß.  There are also half-liter sized, tall glasses.  It's impressive to see the waitresses at the Munich beer halls carrying 8 or more of these maß at one time.  If you go to Munich, make sure you visit the beer halls.  Many of the brewers have their own beer hall right in the city, so you can drink fresh beer brewed right there.
• I know we're talking about German beer, but one can get really good beer from other countries too.  I heartily recommend Belgian beer to the European traveller.  Be warned, though, that Belgian beer comes in 3 different grades, which correspond to their alcohol content.  I think the grades are 7%, 9%, and 11%.  Yes, the highest grade beer has the same alcohol content as wine.  I didn't know this until I had drunk a few of the highest grade.  I also strongly recommend Budweiser.  No, I'm not referring to that American liquid jokingly known as the "King of Beers".  I mean beer from the Czech town of Budweis.  It's one of the best beers I've ever had, almost as good as Dom Kölsch.
• Don't laugh, but I also suggest trying some German wine while there.  The white wine from the Mosel river area is good.  Thanks to the European Union and the elimination of all those tariffs on exports within the Union, Italian and French wines are available at bargain prices.  You can get a decent bottle of Pinot Grigio for under 15 DM.  Not to be missed.  Spanish wine from the Rioja region is a very good red wine.
• Travel  When in Germany, be sure to travel on the railroad.  The Europeans have an extensive and efficient rail system that goes everywhere.  You get to see beautiful landscapes from a comfortable carriage.  The train ride from Frankfurt airport to Bonn was fantastic.  The route follows the Main and Rhein rivers through small, old towns with castle ruins and big churches.  Just beautiful.
• Tourism  If you are going to be a tourist anywhere in the world, take my advice:  Do not get attached to guided tours on your trip.  I cannot say that often enough.  Guided tours give you a very limited view of the place you are visiting.  They emphasize specific tourist locations, and shuttling between them as quickly as possible so you can visit the gift shops and spend your money.  Everywhere I've visted, the most interesting parts of the trip have been, not the major sites, but everything between those sites.  In Paris, the Eiffel Tower and Arc de Triomphe are impressive and not to be missed.  But the most fun I've had in Paris (I've been there 3 times) is just roaming the streets, walking along the river, soaking up the atmosphere.  The same is true in Rome.  My parents visted me in Germany in 1997 and we went to Paris.  I just showed them around myself, and they were glad that we didn't do some package tour.  Don't get me wrong, the guided tours are good for specific sites.  For example, I did a guided tour of Tivoli and Hadrian's palace when in Rome.  But in general, I got much more out of my trips with a simple guide book and my own two feet (and a subway pass) for transport.  I would not have seen anywhere near as much of Rome or Paris if I had been tied to some tour.  So, get out, meet the people, find the more obscure attractions, and relax.  Another recommendation:  save your money and make your own postcards.  The photographic quality of tourist postcards and souvenirs really isn't that high.  You can do it yourself just as well.  At least for me, it means so much more because I took the picture.  The best souvenirs I have of my trips to Paris and Rome are the photographs I made.
• Neo-nazis/right-wing extremists  This is a concern many, both in and out of Germany, have.  Yes, there are neo-nazis and right-wing extremists in Germany.  (They are here in the US too.)  I saw more swastikas in a week in Rome than in 2 years in Germany.  Despite the media coverage these groups get, they are small, numbering perhaps a few thousand people in a nation of 80 million.  These groups are mostly concentrated in the former East Germany, where unemployment, and therefore dissatisfaction, remains exceedingly high.  Anti-foreigner sentiment is primarily focussed on the Turks, who have lived in Germany for generations but have been denied citizenship because they don't have German ancestry (some things never die).  It's no more dangerous in Germany than in the US.  Actually, it's probably much safer.  There is much less violence in Germany than in the US.
• TV  I mention this because Americans may be surprised by German television.  First of all, it's very boring.  But more importantly, restrictions on sexuality are quite loose compared to the US.  Americans get into a huff, and advertisers get nervous, because of a brief shot of a bare breast on US TV.  The Germans have soft-core porn regularly, on ordinary broadcast TV.  (The Spanish have hard-core, XXX movies on ordinary broadcast TV at night.)  So don't be surprised if you are flipping the channels at night in Germany and you come across some naked women.
• Government  Germany is a socialist country, like most of Western Europe.  Be prepared for this, especially if you are moving there.  Republicans in the US love to complain about how big our government is.  Our government is nothing compared to that of Germany.  In Germany, the government must approve the name you give your child when s/he is born.  In Germany, contributions to public TV and radio are mandatory, and pretty hefty.  The government collects the fees and distributes the money to the broadcasters.  (This may be one of the reasons German TV is so boring.)  In Germany, if you declare a religion, contributions to your church are mandatory.  It is collected by the government from your paycheck and the funds distributed as the state sees fit to churches of your denomination or religion.  (My advice:  declare no religion.  Voluntary contributions to your local church is part of your worship of God.  Don't let a government deprive you of that worship.)  There are other effects of socialism that you will experience every day.  Tips for waitpersons are included in the price of your food at a restaurant, though it is customary to leave a token tip, perhaps some change.  Because of this, waitpersons are not motivated to excell in their service to you, and therefore service in restaurants is quite poor.  Be prepared to wait for your food!  Stores close at (from my American perspective) ridiculous hours, though it's gotten better.  When I arrived in Germany, everything closed at 6:30 during the week and 2 PM on Saturdays.  Shortly thereafter, hours were extended to 8 PM during the week and 4 PM on Saturday.  Most things are still closed on Sunday.  Some on Schröder's government want to eliminate government restrictions on hours of operation, but are being met with complaints that the current system already requires workers to work "unsociable" hours.