Also, don't be afraid to mix genre's. I like to use Blues (Jonny Lang, BB King) for climbing, as well as Metal (think Godsmack, Metallica, Drowning Pool), as well as covers of other songs. One of my favorites right now is "Saturday night's alright for Fighting (covered by Kid Rock and Nickleback). Then I've added in classical stuff as well (the 1812 Overture is excellent!).
As another poster mentioned, using all techno can wear on those that aren't fans, so although I love to use it, I do so sparingly.
Vertically challenged, but expanding my horizons.