Robert Atkins, a regular contributor to JoeReloaded.com (and current artist of the G.I. Joe book from IDW) occasionally posts some art on the JoeReloaded forums. Well, he went a bit further this time around and showed off a bunch of art for the cover of Issue #5, including a very early sample, and leading up to the full blown colored final version. Some awesome insight and some great art as well.
Check out the thread here.