XKCD

If you're looking at today's XKCD you might find this handy.

Or for the stupidly ambitious: 
1/8 scale (256x256 tiles): http://edc.srvs.us/1110-eighth/

1/4 scale (512x512 tiles): http://edc.srvs.us/1110-quarter/

1/2 scale (1024x1024 tiles): http://edc.srvs.us/1110-half/

full size (2048x2048 tiles): http://edc.srvs.us/1110/