That Kyuss Touchgraph thing is still being updated (all links are shown already, no need for clicking). It's mostly shared drummers (Brant Bjork, Dave Grohl, Dale Crover) that bring them together. Much information courtesy of allmusic.com. I asked them a few months ago if I could do a Touchgraph of their 'related artists' or 'formal connections' data, but they said no. I think it could have been useful/entertaining.
I also use allmusic (and freedb) with Tag&Rename (Windows) for tagging all my MP3s. The new version is finally released now. You can fetch all the tags in 2 or 3 clicks, and rename the files into folders with another. It's almost perfect.
For converting between music formats, there's nothing better than dBpowerAMP Music Converter. The new version is in beta, and there are codec packs for every format under the sun.
I got the chance to try out DeKstasy a few weeks ago. It's free DJ software for OS X. Basically, you import a bunch of tracks, it automatically beat-analyses them to get the BPM and beat points, then you add them to various 'crates'. Cue up the tracks on the 4-track mixer and it displays the waveform, so you can line up the start and endpoints of each track (snaps to the beat as well). Switch to the BPM page to adjust the speed, then to the mixer page to flick between tracks at the right time. The automatic BPM tool was only right about 50% of the time with the mix of guitar tracks and other stuff I was playing, but I imagine with standard house or techno it should have no problems. It's easy to tap along to set the right BPM anyway.
I also bought the M-Audio Sonica - a USB sound card - that allows programs like DeKstasy to direct one sound output through the USB card and out to the main amplifier while sending another, different, track to your headphones through the iBook's built-in sound card. Still no Panther drivers for the Sonica though, so it's gathering dust at the moment.