Urban Sketchers is having a donation drive for their 3rd anniversary.
For your donation which will go to the educational programs they organize, you'll be getting a high-res digital sketch that you can print out. You can check out the 34 art sketches available on this Flickr page.
If you're donating upwards of $75, you get get one of the sketches below mailed to you.
Visit their website for more information.