The LAME audio codec (Lame Aint an MP3 Encoder) 3.96 is a complete classic for audio programs, being one of the fastest, if not the fastest. It lets you configure the bitrate (128Kbps, 160 Kbps, variable) and the Joint Stereo.
The codec integrates well with applications that need it, like AudioCrusher, Audiograbber, Text Aloud MP3, Easy CD-DA Extraction, CDex, ALF, etc.