Saw it a few posts above.. uo poko Fun
In the same post was Space Zap.. I've been playing that since I got into mame- it's very cool when you get into that "zone" (you know exactly what I mean)
The one I found again today after finding in a similar way before is Butasan. Sorta like dodge ball, with pigs, and gas masks, and exploding balls, and very addictive music
Burglar X is pretty cool also- your character appears to be a skinhead(or a girl) banditoin different maze environments collecting coins. Your main attack is to head-butt the other goofy characters, you also have what appears to be a "fart" button(don't ask), and indestructible motor scooters. Very Bizarre
Probably the strangest I've found is Ganbare Ginkun, which is a ton of mini-games that look like hand drawn stick figures