I'd say pass on RadioDaddy. They seem like an interesting business experiment (kinda like how in sci-fi movies, utopia is always communist), but the ratio of work to benefit seems kinda weighted. Against you.
Also I find them to be kinda pompous and obnoxious about their "service":
The Ramblings of Some Audio Guy: Where I wont go with my Voice: Radiodaddy edition
Digg - Radio Daddy Tells Podcasters to F off
So they get to be exclusive, AND you get to work for free. Seems fair...
If you really want to keep your chops in shape,
AND help a grateful community, I will second both AIRSLA and Librivox. Both are great communities to work with.