Make spaceships in Flash or iOS. Symmetric and asymmetric part placement. Intended for us non-artistic folk (easy to use.) Save them to your computer, then use GIMP to autocrop and adjust hue/saturation.

http://www.astroarmada.com/partart/

The source for this app is at http://sourceforge.net/projects/partartspace/

 It is a Flash app. Made freely using FlashDevelop and Actionscript 3.