I use BBSmart Alarms Pro -- you can set different alarms for different days and so on. Info about it here:
http://www.blackberryforums.com/afte...a-testing.html
That's an old thread -- the app is no longer in beta, it's been released quite a while ago, but there is some good info about it there.
Btw, when posting about or looking for apps the Aftermarket Software forum is the best place.
Whoops, you asked about a free app -- I don't know of a free one.