Lately I've taken to doing any computer-based graphic arts in SVG, which is a very portable and XML-based format. It isn't a binary format like JPEG, PNG, but text, so you can edit it with a text editor that doesn't mangle things. The stuff I have on my web site is in SVG format, seen here:

http://simonraven.kisikew.org/Artwork/

It's a bit messy right now, not having had time lately to organise it more. Some of the stuff isn't really what I'd call my own work, but they're from online tutorials I followed, to learn Inkscape more.