Here is a basic grunge background. Image dimensions are 1600X800px. Took about 10mins to build, PSD included. I started with a center content area size of 960px wide. If you have PhotoShop then you can edit this to fit your needs.
The body CSS for this background:
background: #f9f9f9 url(/images/red-grunge.jpg) top center no-repeat;
PSD Download: Red-Grunge.psd
Twitter Background:
tile background unchecked
Background color: f9f9f9
Text color: b0b0b0
Link color: a10000
Sidebar color: 400102
Sidebar border: c90000
Example Twitter Page:
Hah, I love how you say you pretty much just whipped this up in a few minutes :P. It’s excellent. Keep up the great work!