The fairly incredible indie netlabel Deep Elm Records has a ton of samplers available for free download. There is something for everyone here – from postrock to punk, it all rocks hard. I started with the sampler Postrockology, and I’m working my way through the rest. It’s a mixed bag, and some of the tracks are better than others (there are a few that I just don’t care for at all, but only because if style and substance – everything I’ve heard so far is technically excellent). Definitely go here, check things out. I’m sure you’ll be kept busy for quite some time.
Rock! Garage band type music in the style of Jet, The White Stripes, etc. A great set of rowdy tunes, perfect driving music. Make sure you check out the rest of their site at thevue.com.