I wanted to plug I've been using for a while and it's about to have a site launch so they're asking members to talk up the service. It's called Spoonfed - London's Best Event's Site and does London event listings. It has way more than Time Out or any of the others, especially when it comes to art exhibitions, classes, quiz nites and tournements. You should all check it out!
The best part is, once you register, they give you events based on your interest or your location so you don't have to search through everything in London :).
Hope to see you around!