So the hardest thing about using image or text generators is FINDING them. This one - with the dubious name of PimpMySpace.org (and with some other ahem...questionable options) is one I'm reluctant to mention on a JOB work-related blog but does speak to the diva-wannabee in all of us!
I did find one that creates stereograms but since I've never been able to see those things, I'm not actually sure it works! http://www.eyetricks.com/stereograms/onlinetools/stereocreator.htm
These seem more practical than mash-ups - at least in the right here, right now - but that being said, I am looking forward to turning my husband's picture into a Simpsons character (http://simpsonizeme.com/ and listed on The Generator Blog).