Last summer I visited Beijing for a few days. You already know where to be on Tuesday evenings

Great source of insider knowledge, nice people as well.
The weiqi saloon cdy mentioned is also nice place, I checked once on a weekday. You can find both places address on senseis library.
Google maps of China has wrong gps coordinates - there is a some hundred meters offset.
Taxis are very cheap. Metro is easy to use unless you have heavy luggage (stairs). Airport to city taxi charges ca 100 RMB, though there will be a taxi-queue-handler asking your destination and give a quote around 5 times of that.
I learned the numbers, "how much" and "too expensive" before going, and had fun haggling for things that I didn't really want to buy. They refer to chinese money not as yuan or renminbi, but kuai. Somewhat disappointingly, I saw many people playing xiangqi on the street/parks but never weiqi.
I reckon I am a bit random and should be sleeping already.