Signature Pictures?

[Cyberburn]

I have noticed on some forum sites, that after a post, they will have some typed signature stuff. Fancy sayings, movie quotes, funny phrases ect. Then, below that, there is a rectangle, that has some pictures, or computer drawn images on them, that they made themselves. Some of these signature pictures are quite impressive. I was wanting to know how I were to go about making one of these, or if there was a site that had a tutorial, or instructions on how to make these. Or perhaps a downloadable utility? (Examples of sizes, and such). Also, I would need to know how to incorporate these into the signatures, once they were made.
Would anyone know how to point me in the direction I'm looking?

Thank you very much for your help.

-Cyberburn

[The Tool]

Signature picture isn't enabled here, it makes the page long and takes time to load.

People use Photoshop to make signatures: http://www.adobe.com/products/photoshop/