Tom B. over at Marvel frequently posts B&W images (of various covers, commissions, comic pages, etc) - the ones I enjoy, I save and then digitally recolor. Some of the recoloring are images I got elsewhere (for example, Wendy Pini posted a few B&W images of ElfQuest related stuff I grabbed and colored)...
EDIT: Going to host the images myself for better quality.
Colored Dark Phoenix vs the X-Men
Alpha Flight
Another Alpha Flight: