I love art that is in your face. I particularly enjoy large scale photography that is very graphic in nature. I figure if you are going to stick some art on your walls, make it large, bold and eye-catching, and encourage questions from visitors (like "what in the hell?!"). Here is a collection of photographs I found in my stash that feature some pretty fantastic art (IMHO).
Anthology Magazine - OMG I want this!!!
my favourite of all time, blogged a few times here... Steven Sclaroff
If you're looking for an online resource for artwork, Saatchi Art has everything you could ask for in every medium fathomable, and they even carry original paintings!