Here are some links to music I like to listen to and music/samples which I have created.
Some of my favourite sources for freely available MP3s, MODs and OGGs:
Here are some links to streaming music I like to listen to occasionally:
Of couse, you can always browse the Google Directory and look for streaming MP3 stations you like...
If you're using Linux I can also recommend the streamtuner application which has a huge list of various online radio stations built-in.
Here are some samples (WAV files) which I have recorded. They are all licensed under the terms of the GNU GPL (version 2 or later). You are free to use them to create your own songs or game music, as long as those songs/games are released under the terms of the GPL, too.