If you really are serious about wanting to make desktop mascots, E-mail me. We might be able to put together some interesting collaborations.
What I could use to make the mascots are basically the images to use as cels. They can't be anti-aliased on the outside edge; if they are it'll create that nasty halo effect. The mascots themselves are limited as to what they can do, so you can't get as complicated with their behaviors as if they were KiSS dolls.