If you want to make good signatures like my current or the ones in my newest photobucket album then you need four great websites.

First:
Gamerenders-
This site will provide you with amazing pictures for your signatures. This site also has a section where tutorials of any kind can be found. (Mainly photoshop tutorials) This tutorials will teach you how to use photoshop, how to make a basic signature, and how to make an amazing signature.
Second:
ChaosGFX-
This site is mainly tutorials. It is another great place to find out how to make quality signatures and basic ones for beginners.
Third:
Pixel2Life-
All tutorials. Some great ones and some average ones. Tutorials come from all over the internet from every type of board and will teach you a variety of skills.
Fourth:
Greycobra-
This site also has tutorials, but not as many tutorials as the others. Mainly it has a signature showoff area where people who are skilled in photoshop will comment on your work and help you to better it. It is a great site for critique.

Hope this helps all of you out there. With practise these sites will be able to help you better your photoshop skills. Also, experiment and try to come up with your own personal style. Good luck!