Facebook and Google plus cover photo Generator
Before I go mad with texts, here is the link: http://www.korko.fr/clevercover/
The website so far has no advertising and allows use of both internet images and from you hard drive.
Tutorial (Don't think it's necessary, but still, a post with just a link... no one will ever find it on Google)
Just go to the link choose either Google+ or Facebook and click on it. Now choose local for photos you want to use from you computer. Upload it and fix you setting before downloading. Keep in mind though, you need 940x250 pixels or bigger for Google plus. If you want to use internet photos then get the link and paste it after you click 'Online pictures'. Have fun!