Aacplusenc
aacplusenc is a multiplatform HE-AAC+ encoder.
It was written by Matteo Croce that tooks the 3gpp reference code and wrote his own routine to read wav files,
write RAW ADTS output as well as faster buffered I/O and custom FFT routines.
The encoder now supports mono and stereo encodings, it's not as good as the Nero encoder but is way faster ad quality is quite good.
Also, it's the only HE-AAC+ on certain combination of Operating System/architecture like MacOSX, Linux/PPC etc.
Full source code is available for download on the official site.