OpenSebJ is powering on; with an ever increasing rate of downloads - over 10,000 last month - bringing the total so far to 79,693 (I would have written this latter in the week when it passed 80,000 but I couldn't wait :-)
I have been looking around at the other Open Source audio programs yesterday and then couldn't re-find them all easily this morning; so let me share with you some of the tools I have found and know of so far (All Free Open Source Software (FOSS) with a working Windows Port):
[Obviously my opinions of these programs are just, my opinions]
The best FOSS wave/sample editor. If you want to change any pre-recorded audio this is the tool to use. It has heaps of downloadable effects, can convert, read and write in almost any format (wav, ogg, snd, mp3, etc) and is easy to use.
VioLet Composer: http://sourceforge.net/projects/buzz-like
It's like Buzz but FOSS. Allowing for programmable plug-ins; with the ability to daisy chain events together, mix channels and all bundled in with a Tracker style sequencer. If your looking for a creative outlet for synthesis
Denemo - (A front end to Lilypond) : http://sourceforge.net/projects/denemo/
Lilypond is a score printing tool but Denemo is much more than just that. It allows for scores to be composed completely from scratch in the traditional sense - these scores are exportable out in the MIDI format; although I wasn't able to get the windows port playing the score I composed directly (but I didn't spend any time trying to get it working either ;-) as the MIDI export worked flawlessly. If you want a musical score editor & composer; start right here.
Another score editing tool. Its interface is clean and playing the notes entered on the score works as expected. I did have a few issues (a couple of crashes) while trying to get this going but this is defiantly another tool to keep an eye on.
BestPractice (Time stretching tool): http://www.xs4all.nl/~mp2004/bp/
The biggest honor to bestow is that the tool does what it says it will and this one does. To boot, it also includes a Kareoke option, Semitone adjustment, etc. Nice little tool. It doesn't contain a way of capturing the audio output, so use Audactiy and capture it through the sound card instead.
If you know of more that should be here; drop me a line and let me know about them.