I've found one now! http://www.needcoolshoes.com/

Just to put this who "X skin editor is against the rules to use" to rest, all the people saying that they're allowed as long as you don't include any parts that aren't your own are correct.

So feel freel to use Novaskin, Skindex, Skincraft, and whatever else as long as the resulting skin doesn't contain any pre-made parts you didn't create.

You know, if you actually read the thing, it tells you to keep reading for suggestions on what to use...

I use The Skindex for making skins but I don't use it to post skins as they always get stolen! =/

Dude, it's actually quite easy NOT to steal others parts. you just have to learn how to use it. if anybody want's a tutorial on how to shade using novaskin PM me.

ya i use novaskin i have talked to a mod about it, just don't use any of the things like noise or or steal anyone else's parts

I recommend using two editors.
Use the 3D editor at http://www.needcoolshoes.com/ to lay the base colors and layers, then use Gimp http://www.gimp.org/ to add the finishing touches like shading and such.
I use this strategy for making my skins, it's very effective.

Paint.NET

or you could use NovaSkin I guess.
It's quite easy to use;
but I only use it for posing people for images.

List some editors you already used so people don't recommend those ones