Most music player apps that you can download should play .wma files. I found that I like PowerAmp very much on my Comet. There's a problem with wma files though, and it's the OS's (Froyo) fault and not any one app. For some reason, Froyo, which manages the music database instead of your music app, does not recognize the "artist" tag in wma files. It's hugely inconvenient for those of us who browse our music via metadata like that. So much so that I resorted to converting all my wmas to mp3s during the transfer from my computer to my microSD card. Good luck!
