Can you find free comic book artwork to use legally on the Internet?

I don't think most artists want their work to be used like that, unless they're given credit for it somehow. If you do use someone else's comics, I'd advise that you link back to their site to avoid a copyright issue. You could also commission someone to draw for you, but that typically costs money.

A good place to start would be, do a search on the Creative Commons license. It's an effort by creative folks to make works more accessible and user-friendly while still protecting the rights of the creators. You may get lucky and find a number of artists that don't mind you using their work so long as you attribute the work to them and give them some link love.

Gooogle it... or try http//:google.com/comicmania