Some builds still completing, don't use the *-debug builds: http://ftp.mozilla.org/pub/mozilla.org/firefox/tryserver-builds/david.humphrey@senecac.on.ca-6b76c851e3f7/ The Linux/Windows builds do not have working WebGL at this time due to [https://bugzilla.mozilla.org/show_bug.cgi?id=567095 bug 567095].
By request, a [http://scotland.proximity.on.ca/dxr/tmp/audio/audio13a/firefox-3.7a5pre.en-US.linux-x86_64.tar.bz2 Fedora Linux 64-bit build] is available too.
A version of Firefox combining [https://bugzilla.mozilla.org/show_bug.cgi?id=508906 Multi-Touch screen input from Felipe Gomes] and audio data access from David Humphrey can be downloaded [http://gul.ly/5q here].