I will assume you are aware of all the obvious ones.. anyway here are some of my less well known favourites.. +1 for Harmful Park, Tempest X3, N20: Nitrous Oxide, Space Shot, Night Raid, X2 No Relief, Soukyugurentai (terra diver), Philosoma, Omega Boost, Sonic Wings Special, Salamander 2, Mobile Light Force, Nanotek Warrior, Gatchaman: the shooting, Stahlfeder, IS: Internal Section, Gamera 2000 (yes i do LOVE shmups!!)