What kind of arcade games do you like? I prefer shmups and 2D fighters myself, though I also like games like Pac-Man and Donkey Kong too.

Recently I went on a downloading rampage for my MAME folder and now I have plenty to keep me busy. However, none of them match up to the CAVE shmups Necronopticous sent me (DoDonPachi, ESP Ra.De., Guwange, Progear, etc.)...

Anyway, what are your favorite arcade/arcade-style games, and what would you recommend for someone (me) looking to expand their collection?