I'm just wondering, haha ^^

Paint Tool SAI. c':

I use Adobe Photoshop for mine. ^^

Photoshop Elements 6.0 |D I use Paint Tool SAI on occasions for lineart.

I use GIMP2.0, a free download from the internet. I'd prefer using a program where I can place lines and curve them, but there is no tool for that on GIMP, which is very difficult on a trackpad.