Having restrictions on the signature would be cool, so we could protect our forums from spamming and keep em clean without installing 10 hooks

There are signature restrictions already if I remember correctly... but it depends on what you really thinking about?

Having restrictions on the signature would be cool, so we could protect our forums from spamming and keep em clean without installing 10 hooks

What kind of restriction did you have in mind? It would help if you mentioned them so the Ipb staff can have an idea of what you mean.

like for example

• disallow url
• set a max font size
  

IMHO, the signature is the most abused feature by the regular members because its forum-wide effect and its 'just saying' nature.

If I could make the restriction for the signature, I would allow only plain color with bold and italic formatting.