Soho, hang get out at Covent Garden tube station, wander round the piazza, cool place. Walk down Neal Street to leicester square, find the small streets! Great vibe north of Leicester Square, through to China Town, and the seedy peep shows (not many left but SO seedy!)
Oxford street is okay, there is a phantastic retro games shop, you have to go left up a street just before Totenham Court road (can't remember whic, just after Game...?). HMV is huge, worth a wander! Up Totenham Court road, you can buy kinda cheap electroogoods (not that cheap, but good for window shopping!).
Hyde park is cool, when the sunshines! Regents park is better for ogling.
The National Gallery is free, and is amazing, whether you like art or not. You can dooa tour of Buckingham Palace. The Cinemas on Leicester square cost a fortune, but are worth it. The Imax cinema on the south bank is superb! The royal opera is cheap if you buy a day ticket (it's great too-no really it is!), The theatres in the west end nearly all have tickets for sale, so avoid the touts and booths (matinees are good and cheap-avoid the mousetrap!!!!).
London eye if you like queueing. Madame Tussards is ok, Tower of London interesting. London Zoo is excellent.
Clubs, been a while since I was clubbing in London, so your best bet is to pick up a copy of Time out and look there (a very good magazine- buy one anyway as it covers everything from gay culture to opera/ballet. essential purchase.)
Avoid the underground (especially rush hour!), buses are better but slower. Try a tour bus (never done one!)
Weekends head up to Camden Town. Watch your Wallent EVERYWHERE!!!
Holland park, notting hill-lots of small village type suberbs that are worth wandering around.
Email me if you wanna know anything else. It's a great huge (it's HUGE) city, with so many different parts. There is whatever you want. But I hated living there. Now I miss it (a big city in Germany has about 1 million, london has 17 million!!!!).
My fav spot is around the Piazza at covent garden.