Personal Paint is my choice for pixelling on my Amiga, I use it more than any other program. It's free and on Aminet. If you're going for a full CD, why not include a few extra programs that do the same thing, to give people a choice themselves. I really like the idea of a new, updated PD CD. There are a couple of programs which don't really fit in a specific category but are fun to try and can be quite useful for a game developer, CopColEd and Havoc Rainbows. Anyway try them out and see what you think.
Havoc Rainbows - http://aminet.net/package/dev/amos/hrainbows
CopColEd - http://aminet.net/package/dev/moni/CopColEdV12
Personal Paint - http://aminet.net/package/biz/cloan/PPaint