Manic miner was fab! My mum says that hearing that tune coming out of my bedroom for hours and days on end drove her up the wall!
Knickknack if you do get WoW I'd recommend starting as a night elf. It was the best character I started, as a new area and race it benefitted from the experience of the older areas. i think they're doing a new expansion pack soon with a new race so that would probably be the best written so far.
WoW costs - to the tune of about nine quid a month - when I write that down it seems ridiculous! You can stop it/buy shorter times and in dormant periods they keep all your characters - so you can take a break for a year or two and pick up where you left off.
Still it's a lot of money. DH has conditioned me...!!