Free stuff is good. And good free stuff is even better. That's why Audacity is absolutely great. It's a lightweight, free (as in "freedom"), cross-platform audio recording and editing program which can handle Ogg Vorbis, MP3, WAV or AIFF sound files.
If you're recording and tweaking media clips for your Android or iPhone apps, it's an indespensible tool. It goes from basic recording, trimming and fading ins and outs, to adding compression / normalization, eqs and filters, and a fair range of effects as well as pop and hiss removal, out of the box.
Depending on your audio recording hardware it can also function as a fully-fledged multitrack recorder.
Changes you'll find in version 2.0.0 include:
Scribbled by Tom