I'm really loving Anju's character song right now.

The guitar parts are pretty awesome sounding.

http://www.youtube.com/watch?v=t3zgRLlJ4O8

Karin's character song is more of a silly song. It's supposed to be about her as a masked crime fighter named, "Zouketsu Kamen". XD

http://www.youtube.com/watch?v=_D5U__X0brA

Maki's is more serious and she has a pretty good singing voice too:

http://www.youtube.com/watch?v=pX8ZlW8gZa8

And here's Karin and Anju singing a silly song together:

http://www.youtube.com/watch?v=Z0WiotyEMJE

I know people are wondering about the other characters, but they don't have any other character songs.

But here's the closest thing I could find to Kenta singing (listen to the parts with Kamina pics-the dude with huge glasses and low voice-, the guy who does his voice does Kenta's voice too):

http://www.youtube.com/watch?v=HWSFBc77gXw

Kenta's drama CD voice is done by this guy:

http://www.youtube.com/watch?v=LWehlfHwRMI

And here's the closest thing I could find to Ren singing (Archer's voice is pretty similar) :

http://www.youtube.com/watch?v=mm4uIpAXpUg