This has been bugging me for ages but I really don't understand why people have massive sigs.
The most common type of sig is stating what you own, does anyone really want to know? I doubt there would be a situation where I would read someones sig and notice a game I like and talk to them about it...it just seems really pointless.
The other common theme of sigs is to quote a funny line by someone else on the forums. In rare cases these can be funny, but most of the time I find them to be inside jokes, the punchline has been taken completley out of context and it's not funny anymore.
Links to stuff like the piracy policy are ok, as long as its not too obstructive. Even then I think the mods should have this, it saves them posting a link to the piracy policy all the time, they should just say 'see sig'. For other members though it doesn't make much difference, if a noob wont search before posting, they wont bother to click on links either, they want to be told directly what to do.
I am not saying ban sigs, but at least impose a maximum size limit on them.