HelRazor
Thanks for the great tip. I've actually been playing around lately with multiband compression on my bass track with side chain triggering. I produce electronic music and want a prominent 4x4 kick, so I've got the kick triggering the compression on the lowest band on the bass synth so it ducks. I like using the Waves C6 which happens to be on sale now, and I'm sure there's other great multiband compressors with sidechaining as well.
The L-Phase Multiband in SONAR provides selectable per-band sidechaining. So if you want to sidechain only the lowest band, no problem. If the CPU hit is too much, use non-linear mode.
Also don't forget that the Sonitus Multiband makes a great crossover for feeding other plug-ins. For example, you could split off just the low end and feed that into a sidechained gate.