I do the following for backups:
24bit master WAV on DVD+R
24bit master FLAC on DVD+R
24bit edited and tracked FLAC on DVD+R & external HD (Squeezebox 3 library)
24bit edited and tracked on DVD-A
16bit edited and tracked FLAC on DVD+R & external HD (Squeezebox 3 library)
16bit edited and tracked on CD-R
I also keep most of the FLACs on my internal HD (but I haven't taped nearly the amount of shows as some/most of you). As a result, they are also on another external HD that is a monthly mirror of my internal HD. I back up my internal HD files weekly (or before/after a major change) to an external HD as well, so many of the FLACs are backed up there as well. This is all in addition to trading most of my recordings via BT, FTP, archive, etc. I think I'm pretty well covered