You're not the Ace from American Idol by any chance, are you?
If so, be sure to come back here and post a link to your blog.
There's only one, that I know of, that satisfies all your needs.
The eSnips site offers 1GB storage, and uploads of any filetype,
and your shared files are made available by making a page public
or inviting others by email. You can add posts to the pages with
the mp3 files on them, and visitors can add posts to comment.
It's not exactly a regular blog, and your options for changing
the appearance of the pages is very limited, but it fulfills all
the options most blogs offer, and it's completely free!
Here's a page by a musician, so you can get a feel for the layout:
Assuming you have the rights to the files you're planning to publish,
this may be the best solution available at no cost. I'm sure that the
terms of service prohibit publishing copyrighted music files on the
Another site is Writely, which allows you 1GB storage, the ability
to create a document in a Word-type environment and later publish
that page in HTML on your own blog page on their site. Unfortunately,
they are in Beta, so you need to be invited via email address, which
is not allowed on Google Answers. Also, they currently cater to the
business market, so mp3 files are not among the files which can be
uploaded - only document files, thus far. It's also free, and was
just obtained by Google. Whether they'll someday allow mp3 files
to be uploaded and linked in the blog is anybody's guess.
Let me know if you have any questions...