Signature generators

[Zplinter]

The enjin one does not work to my taste as it messes up the head portrait badly on my toon, so I had to fiddle around and make my own. I can not find another site still making them automatically.

[JillyBean]

Mine is from xivpads, is that one no longer around? They used to have tons of member created templates

[UltimateAoe2]

Because if I made own, its quality wouldn't be high enough for me to like it. -_-

Well, it shouldn't be /too/ hard. You just need to look online for some custom brushes or try to make one using Photoshop's available tools.
The most basic way is to cut out your character using the Lasso Tool, and work around that.
Some examples of what I mean:

(taken from photoshop itself, cause it won't damn export properly. Which is why you see the transparent background. .

Try looking for a theme for your character, and again, go from there. Some screenshots you can take from in-game prove really good .
Practice gives good results when you put the effort into it!

[Zplinter]

Their site is not there anymore jilly.

[Atamos]

Yup make your own, it's more fun, I should update mine, it's from 1.0. :')

[Pruviant]

I use the polygon cutout tool and zoom in to like 300%. Makes it a ton cleaner ... the one below I threw together in 5 mins or so, just practice and you will get it!!