Last.fm would be your best bet since some people have no idea of how to go through the process of unzipping files.
Here's an example of a band that is providing some free music:
Evil Empire – Discover music, videos, concerts, & pictures at Last.fm
If you scroll towards the bottom right above the shoutbox where it keeps track of how often your tracks are played you it gives people the option to download them for free.
But if you wanted to go about giving out full albums for free using Megaupload like LoathsomePete said would be your best bet.