I found these sites on the web. I'm sure that the original authors didn't intend them to be funny, but they're good for a giggle. (Just make sure to proofread your work.)

Check out Shameful Typos. There are a lot of funny ones there.

This site has pictures of 10 very funny typos. (Some of the typos ended up being PG-13.)

And in case there aren't enough typos in the world, you can use this site to create your own.