Yeah, Ikaruga was a classic. For very traditional "bullet hell" stuff, I recommend you start with the Touhou Project (a million games, all of them are essentially the same thing). I've also been playing a lot of Jamestown lately. Unfortunately, I'm running on very little sleep and nothing is else to coming to mind, but definitely check those out.

Ah, thank you. I'm not looking so much for bullet hell stuff, there were less bullets than this, but I remember ground vehicles you could destroy, nice graphics (maybe on the Neo Geo?), powerups, things like that. It was a military installation-themed thing...