Web casts, online radio, VOIP apps or a audio/video song playing through your speakers... the Audio Recorder will grab and record it into several different formats such as mp3, ogg, FLAC and WAV formats. Being a GTK+ based app it is easy to use and simple as well.
If you use Ubuntu 10.10 or 11.04 alpha then you can easily install it using PPA. First open your terminal and issue the below commands.
sudo apt-add-repository ppa:osmoma/audio-recorder
sudo apt-get update && sudo apt-get install audio-recorder