My go-to sources to find new skins in Minecraft are the Skindex and Planet Minecraft.
There are lots of skins to download from both sites. I think the Skindex has more, but I like Planet Minecraft’s community a lot more.
My Favorite Skins from the Skindex
This is just a sample of some of my favorite skins found on the Skindex site.
I’ve also been playing around with a program called Mine-imator. It’s a specialized 3D program for creating Minecraft shorts and animations. It’s also perfect for creating really nice rendered screenshots of your avatar wearing great skins. I will post a longer review of Mine-imator soon!