On the other hand, they might be using the computer program because it's easier to output a .jpg for members to see, instead of drawing, then scanning, then compressing, then posting.
The computer's just a tool, and in my opinion a more cumbersome rather than 'easier' one. To me, a better way of going about it would be to draw on paper with a pencil, as Drak suggested, then scan it in and 'trace' around the outside of it using a vector-drawing program such as CorelDraw or Adobe Illustrator. Then you'll have clean lines AND an original design.
However, it takes more work than either computer OR paper alone. As Drak mentioned, the more effort you're willing to put into it, the better your design could turn out.
I agree that all of the above designs so far (with Alex's being the best so far) are still just variations on a superstrat theme. Frankly, I find 'original' designs aren't something I'm overly concerned with, though-- there are plenty of designs out there that I'd like to copy... Les Paul, Steinberger 'broom' (L-series? I dunno!), tele, strat, Axis. That's just me, though, and I understand why people would like to have a purely original design.
Greg