I printed this little toy catapult that appeared on Thingiverse recently http://www.thingiverse.com/thing:23051 . Can't say it chucks a penny very far, which is probably a good thing since it got taken to school by my son the following day! I'm sure the teacher just loved me for printing it! :-)
I shot a little bit of video of it printing. If I recall the settings correctly I'm running 40mm/sec on Perimeters and 60mm/sec on infill, first layer at 50% speed. I used the latest Slic3r to generate the gcode, and am running Marlin on my Gen6 hardware. Here's the video...
If you're not bored yet, here's some bonus material of the infill in action, and the last clip shows the last solid layers going in!
As always, comments and questions welcome.