If you wanna record from your sound card, you can use freeware Freecorder Toolbar or Jaksta Free Media Recorder. They work on many Realtek and SigmaTel soundcards, even on those that don't support recording!

Most MP3 streams are broadcasted with Shoutcast/Icecast servers and can be downloaded using many audio stream rippers that support Shoutcast compatible servers.

Some MP3 are broadcasted through the RTMP protocol. You can use RTMP Flash stream recorders like Replay Media Catcher to download RTMP .MP3 streams from adobe flash player.

All audio stream recording programs should be used as personal archiving tools only, so unfortunately I can't record any MP3s for you.