The only thing I can possibly think of which gets my adrenaline going is highly skilled players in Bomberman Live. I'm currently rank 8 on the Bomberman Live leaderboard, although meaningless, it should tell you that I play the game a lot. Here's some of the people which I've played with before:
http://www.nicovideo.jp/watch/sm6532116 - particularly shimonohashi, PlusYukihiro and midnight are exceptionally skilled. I frequently play with shimonohashi and ht taktaknet, and they're both fun to play against.
As for shmups, no bosses really make me go "holy shit" except for maybe the final attack in ESPGaluda. Unless I'm playing with a stick, in which case, everything becomes extremely difficult and I have a difficult time doing basic things which I can normally pass with a Saturn pad. Here's the final attack I'm talking about:
http://www.nicovideo.jp/watch/sm2032011Of course this isn't to say that I don't die to other things in this or other games, but they don't have any wow factor to them.