I just finished coding the signatures; you may find them familiar
. To see them, click on a user's name or that snazzy arrow to the left of it. To close the sig, click the arrow or the name again.
To add/edit a signature, go to your profile >> forum profile >> edit signature. Bold, italic, strikethrough, underline, and urls are allowed. Everything else isn't. That means no images.
Remember, this is still very much fresh code and there may be bugs. Please report them here or in the support forum. Thanks very much.