This image of a large green sea turtle is available as both a large transparent png and a scalable vector graphic.
Here's a cute graphic of a tortoise (or turtle, to be honest I'm not quite sure of the difference between the two).
Cartoon of a turtle running, wearing glasses.
Well this little guy sure looks happy as he jumps up and down surrounded by flowers.
This picture shows a sea turtle out for a swim.
A cute little animation of a green turtle leaning agains the wall, smiling while tapping his toes.
A small picture of a tortoise with a green shell and skin.
Cartoon of a turtle flipped onto his shell.
Similar to the last one, it's another animation of a tortoise flipped onto it's back and can't get back on it's feet.
Who says turtles have to be slow moving? This cartoon showing one skateboarding seems to show their more creative side. ;)