bumpage for an 18 month old thread.
[name and shame]
Particular culprits in my opinion (and this is by no means a definitive list) are
Red Heat banners - I've got a twin monitor setup at work and still find them to be quite wide.
sjt19 - Sam duder, your sig image is over 3/4 of a Meg - really, if you need that much going on in your sig, use a flash movie.
Some of the Lincoln Storm guys as well - bloody huge width going on there.
Paul Colliers Evil Sharks image is a good 1/3 of a MB too.
[/name and shame]
Yes, I know I can turn off sigs and avatars, but I sometimes browse from machines where I can't/don't want to sign in - ni which case it's scrolling sideways and waiting three weeks for the sigs to download.