Devil's Due published a variety of special comics over years. Convention specials, art books, Free Comic Book Day issues, etc. Look below to see them all:
GI Joe One Shot
Digest/Manga sized book printed in May 2005, an original stand alone story & is part of the official continuity.
Arashikage Showdown
GI Joe Convention Specials
2001 Convention Special
2002 Convention Special
2002 GI Joe Collector's Club
2003 Mix Tape
2003 Convention Mix Tape
2004 Convention Special
Previews, Free Comic Book Day & Art/Poster Specials