Hmm, you have a good idea here with the prepackaged coin logo thing, but you'll find that devs are looking for a unique logo for their coins, and are going to want a, once again, unique design, that descriptively joins the logo to the name of the coin. Might I suggest offering an extra service for customization?
Good luck, and I do dig a few of those designs.
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)