Assassin Xaero said:
Hell, if rap music ([small]haha oxymoron[/small]) is a form of art, then tell me how video games aren't.
http://www.youtube.com/watch?v=SwPEdp70VSE
http://www.youtube.com/watch?v=6MXGIIH93ro&feature=related
http://www.youtube.com/watch?v=PldfoVlsz8o&feature=related
edit:
http://www.youtube.com/watch?v=6l8Gbo8P6dg - just to show beat also allows for fantastic emotional response... again, sadly, you'd need to know the language :\
If you understand the language (sadly 'tis unlikely) and don't illicit an emotional response to any of those 4 songs (particularly the third), I'd pretty much class you off as a psychopath (mean that in the literal sense of the word, not as an insult

).
OT: Agree most with whoever said to give a definition of art that doesn't involve subjectivity, but in the spirit of the question/thread, I'd say Syberia and Syberia 2. I'd also agree with one of the above posters on Grim Fandango (played a bit through it again recently-ish, sadly not to the end due to crashing issues

) and obviously horror games like early Silent Hill/Resident Evil.
Also, really, see Extra Credits on horror games (since fear is an emotion and therefore scary pictures/movies/games are art) they summarize it perfectly, games are the best medium for it cause you virtually walk into fear yourself and not just have it shown to you, you're part of the experience.