This is a copy of the post I just put in the announcement forum, but since it covers a rule, I thought I'd post here as well.

Quote Originally Posted by Bruno
Due to some recent issues, we've had to formalize our stance on sig lines.
We've tried to keep it short and simple:

Free expression: ok
Non-advertisement links: ok
Shaving Advertisement (Tasteful): ok
Other advertisement links: not ok

And for the rest the default site rules apply, so no spam, no abusive language, etc etc.
We don't want to make it too specific. If in doubt, then just ask a mod.