The Cutest Blog on the Block has some really nice free blog backgrounds.
They are backgrounds, not templates, so you don't have to redo your link lists, widgets, etc.!
You just go to the site, choose a background, grab the code and stick it where it says "HTML" after clicking "Add a Gadget." Very simple.
I put backgrounds on all my blogs last night and this is the one I'm most happy with:
http://ihatethekitchen.blogspot.comTake a look at the site and see what they have!
Since it is a background you do need to pick a color that coordinates with the existing elements of your blog, although Blogger does give you some control over the colors and fonts of your blog.