I've taken all the calibration prints out there and condensed them into one place. I have here:
.5mm thin wall
20mm box
20mm hollow box
50mm tower
perimeter width/t tester
precision block
overhang test
oozebane test
bridge test
and more to come.
All designs are my original work and not taken from other users. But they are inspired by other users.
The 20mm box, thin wall, and 50mm tower are ideas from Spacexula's great calibration set http://www.thingiverse.com/thing:2064, and the other ones are my ideas and not influenced by others. After Spacexula's calibration set, there is quite a derivative tree.
Here are some combos I have found with my MK5 extruder:
(In order of: Layer Height, Width/Thickness, Feedrate, Flowrate PWM)
.36, 1.528, 34.1, 255
.3, 1.789, 42, 255
.2, 2.521, 35, 197 *This is still experimental, most prints I try with it fail :(