I've just finished posting a major update to my radio client roundup (more precisely, in the second part).
In it, I review two radio applications containing a timer - one, Clock Radio, containing even a very nice and big clock. Incidentally, the latter is at a 66% off this weekend and is offered for $1 only. (Hurry up if you need it.)
I've also elaborated on which radio clients can be put in the bckground on jailbroken devices.