Just to add if you want to make your own....
This is from the rules forum...
** Signature Lines/Photos **
We are now requiring signature pictures to be within 50 pixels of 468 X 100. Thus the MAXIMUM width of signature pictures is now 518 pixels and the MAXIMUM height is 150 pixels. However, we definitely PREFER 468 X 100. Signatures are also limited to ONE (1) picture ONLY!
Political, War and Religion Signatures And Avatars are not allowed.