Nice starter pack. Personally, I wouldn't have bothered with the GBC port of Crystalis...the NES version blows it out of the water completely. Has horrible synthesized voices that just make you go "WTF?"
Couple more I'll suggest: Ninja Gaiden: Shadow, Batman: The Video Game, Battletoads (first one...not Ragnorok's World), Gargoyle's Quest, and Cosmo Tank.
Greg, don't bother with Ninja Boy 2 on GB...it's pretty bad. I only have it in my collection because I got it for $35 a few years ago. Found out shortly after I got it that it's one of the rarest games on the system. (Last one listed on ebay had a buy it now of like $1,700...way overpriced, BTW) GB collectors go nuts for that game.
When it comes to rare games, unfortunately, they fall into one of two different categories: They're either really good/amazing or, complete shit. No way around it...GB is no different, either. For every Trip World, there's Fish Dude. For every Spud's Adventure, there's Out of Gas. For every Chikyuu Kaihou Gun: ZAS, there's Ninja Boy 2. Etc, etc.
Jon