Would be nice to know what you're looking for, your resolution, etc.
Here's a bunch I use/have used:
https://i.servimg.com/u/f19/14/69/15/92/12618910.jpg
https://i.servimg.com/u/f19/14/69/15/92/wallpa10.jpg
https://i.servimg.com/u/f19/14/69/15/92/12618810.jpg
https://i.servimg.com/u/f19/14/69/15/92/abstra10.jpg
https://i.servimg.com/u/f19/14/69/15/92/abstra11.jpg
You can take a look at www.wincustomize.com , they have some good wallpapers and such.
Edit: Another good place to look (as shameful as it is) is the wallpaper/general section of 4chan.