Okay, these are just 2 backgrounds I like to use. Here's how.
Background 1 1- Open new window with whatever size you use.
2-Click on the brush icon and choose GIMP Brush#2.
3- Brush Over Your Sig
4-Filters < Distorts < Polar Coords::Settings Circle Depth Percent = 0% Play around with the other thing
5-Brush Over Again
6-Filters < Edge Detect < Neon
7-Script-Fu < Animators < Rippling
8-Script-Fu < Alchemy < Erase Every Other Row
9-Filters < Distorts < Polar Coords
10-Settings < Circle in Depth Percent = 0.00% Offset Angle = 182. 40
11-Filters < Repeat "Polar Coords".
12-Brush Over Again
13-Filters < Edge Detect < Edge
This should be your finsished result.
Background 2 Simple but cool.
1-Click on brushes and pick GIMPBRUSH#5.
2-Brush Over the sig.
3-Script-Fu < Alchemy < Weave
4-Script-Fu < Decor < Old Photo(Should bring up new window)
5-Script-Fu < Alchemy < Predator
Finished result.
Thats it.
Nothing special, but I liked them.
*Saving them fucked them up a bit, they look much better when you use them in a sig.