One of the new applications I am excited about on the iphone, which you can also get for your ipod touch is Pandora!! If you are unfamiliar with Pandora, it is a free online streaming radio experience in which you create your own stations with a band or song you love, and it will play similar music selections. I have found lots of great tunes this way. Go (re) acquaint yourself. It has recently improved.
(btw.. can you believe they sold 1 million 3g iphones the first weekend? crazy...eh )