Better still, you could create an "mp3" group, and grant that group read, write and execute permissions.
Creating the group is pretty easy in Netinfo Manager (located in the Utilities folder). Open the app, authenticate yourself (click the lock) then click on groups. You'll see that each group has a name, a password, and a gid (group ID number) and a list of users in the group.
The password field is holdover from ancient UNIX history, and for security reasons should always be set to "*". The gid is the unique identifier that differentiates one group from another (well, that and the name, but when it comes right down to it, the OS uses the gid). the name is the convenient handle for humans to refer to the group. It is good UNIX manners to reserve the first 100 gids for the system. In practice, I like to start my additional gids at 1000 or even 10000.
Once you've found the groups, just pick one and duplicate it. (it will be easier if you pick one with at least one user, "admin" works well). Then edit the copy, so that its name is "mp3" (or "itunes" or "kumquat" or whatever) and it's gid is 1001 or 100001. Edit the "users" list to include each user who should have access (use the OSX "short name"). Save changes and quit Netinfo Manager.
Then, it's just a matter of changing the permission on the mp3 folder to grant all access to your new group. You can do this on the command line with chmod, or just use get info in the finder or any number of shareware permission utilities.
This method is nice because you can allow some users access and deny others, as opposed to a world-writable directory. This is especially nice if you are running an ftp or web server on your machine, as you would want local users to be able to write to the directory, but you probably don't want web users or anonymous ftp sessions to (over)write your mp3s.
Hope this helps...
-alex
