If you ever have the need to convert audio and video files (such as those pesky protected WMAs you can't put on your iPod), MMConvert is the answer. You can quickly and easily convert to and from many formats, including WMA, WMV, AVI, MP3, and OGG (plus a few more). You can batch convert and choose between multiple codecs. It's really a necessity for anyone who likes music or videos.
If you have a lot of WMA files and want to use those same files on an iPod (which doesn't read WMA) without having to purchase them again from iTunes, you can use MMConvert to convert them to MP3 (which can be used on both iPods and other MP3 players).
Homepage --> mmconvert.sourceforge.net