If you have been playing Minecraft for any length of time, then it's a safe bet you've been at least rooting around a little in the Minecraft forums.
If you have been there recently, then you may have seen a post about a little program called MCSkin3D a program which a friend of mine has been working on for about 2 weeks now. It has been getting quite a lot of attention in the last few days, and I have been the one making the icons for the program, but I have also been doing template skins for people to use in the program itself. If you play Minecraft and are looking to make a new skin, it would certainly be worth your time to check it out.
as of right now, you can only edit character skins, but paril is planning on eventually adding texture pack and mob support into the program~! no utility or program has appeared yet to do that in the minecraft community and he's certainly working hard on it! Meanwhile I'll continue to update with as many skins as I possibly can to make available for people to use.