I believe that as a forum gets bigger you can't just use judgement on 'oh that looks too big', because being subjective and you'll get people saying 'he was allowed to do it, why can't i'
Most people are sensible with sigs here but maybe if there was a size limit in terms of both pixels and kb it could be helpful.
Ie x lines of text at normal font size when viewed from 1200x800 (or whatever it is) resolution, or can be no bigger than x pixels in length with combined pictures and text.
I know you can turn off signatures altogether but a lot of them are helpful to see what subjects people do etc
On another note, some transparency between the mods and the common plebs would be nice in terms of what suggestions are being done/considered (ie I have not heard from my mod actions suggestion but I know they tend to write Moderator Action when they do some mod things but not others now, and it would be nice to see their codes they operate on so I can understand them, and if I should be aware of this at all or any requirements I must follow as a subject mod
)