To keep this short and simple: I think forum signatures should have a longer character limit, like waaaaay longer.
It's really fun to add things meaningful to that particular forum's focus in your signature. For example, on this massive forum for ball-jointed dolls that I belong to, we all list our favorite dolls collected in our signature or provide links to our wanted threads, Flickr accounts, etc. When a member talks about X doll by his or her name, we know from their signature what doll they're is talking about or can find a commonality based off of their preferences versus our own. That forum's signature character limit I believe is 1,000 characters including BB markup, this one is a small 255 characters including BB markup.
If this upgrade was implemented, I'd even consider making the limit longer than 1,000 characters to account for how long URLs and SLURLs can be as I'm sure they'd become a major component of signatures, many people have several shops and threads. But this is totally up to KittyCatS of course, and I'm sure they'll find a good signature character number if they alter it.
I think something like this would be awesome for showing off our favorite cattery members or our current breeding projects. Or it could be utilized to post alternate shop locations, easily link to our wanted or selling threads, or add amusing cat-related quotes without having it cut off so early on like it does now. I'm sure there's plenty more that signatures could be utilized for if the character limit was drastically extended.
We already have signatures, I just think they should be longer. More personalization is a plus. \o/
Please consider!