PartArt: Space is all about making higher quality spaceships quickly and easily. Simply select the parts you want, move them around using the buttons or asdwqe keys, and finally save your creation to your computer with a transparent background.
Ships are compatible with commercial projects - just mention Skorpio.
To make the saved images more useful, open them in GIMP, autocrop them, adjust hue/saturation to get the desired colors, and scale them down to the point that the seams are less...