I got hooked on "Omoshiro Minori Housoukyoku," an internet radio that started on 2006-10-13 and still airing at onsen.ag, and since I don't play games, I wanted to support them somehow, so I picked up the drama CDs. I didn't know anything about the characters, but it still wasn't all that hard to get to know them enough to enjoy the dramas.
I doubt there're all that many people like me, so what I write here probably isn't all that useful, so I'll just say that Yamada Yuna is one of the more interesting radio personalities I've come across. In fact, the fact that she doesn't have a very large role in these drama tracks is a bit disappointing.