I know I'm going to get flamed for this, but tough ****.

When I got started on the Internet a decade ago, before the web took off, and messages were really limited to e-mail and USENET (and similar news systems), there was an informal "four line .signature" rule. When I've used a .sig on any BBS, Web forum, or other board (including Usenet), I've tended to follow this. These days, I tend not to use any .sig's at all. Too much trouble to keep updated rather than just typing 'vi .signature' somewhere.

Edit: I thought this was the case and it is. You CAN turn off options to view user's signatures AND avatars in the forums.