Yeah the X68000 is really a great system. A friend of mine has at least on of these and a lot of games. The arcade conversions are really impressive and there are IMHO some of the best ports around on this box.
My personal favourite game for this machine is Cho Ren Sha. Check it out, it's really impressive what this machine is capable of:
http://www.youtube.com/watch?v=ahk8-mFHXYIThis game was a giveaway if I remember correctly. And you should definitely check out Nemesis '90 Kai, one of the best games in that series:
http://www.youtube.com/watch?v=HNEBRl07t50The friend of mine knows a lot about that machine. He even has a Mo-Drive conneted to it, so that he can play games off that drive. He has a german webpage about this and other machines:
http://japan-retro.de/I love this machine!