I started here because i was working nights and the computer network i was on had banned all games sites, but for some reason Chessatwork.com got through the filter because it had 'work' in the title and was didn't mention 'game' anywhere on the homepage. I was just starting out at chess and was playing a lot of blitz on yahoo. I found the site incredibly slow at first and only signed up because sitting on a 12 hour shift with only 6 games going became very boring (refreshing the page once or twice a minute).
Well, it wasn't long before i totally ditched playing blitz in favour of correspondence full time. I'd probably still be floating somewhere in the 1400's if it wasn't for this site. Correspondence really taught me the depth of this game (still is teaching me). The concept of analysing a move, going away for a day or two, coming back and looking again. Sometimes doing this repeatedly over a week or two. It doesn't matter how many times you come back to a single position, there is always some subtlety that you over looked the first time.
I also got hooked on the forums. I used to spend hours in debates until i realised that you just end up repeating yourself over and over as new people join a discussion. I only use the chess forum now, it's much harder for people to fall out talking about chess.