I get a lot of ideas from studio guys. Actually I exchange quite a few. Live sound has gotten to a point in the last few years where it's good enough that you can start to do studio type things like have large diaphragm condenser mics on stage. I really like it when I wind up talking to a studio cat at a show and manage to surprise him with something I'm doing. Usually it's something silly and low brow like using a dynamic mic for a drum overhead in a small bar. For a guy who's used to looking for the cleanest, clearest mic, it's kind of a foreign concept to use one that's better at rejecting extra sounds.
Anyway, the trick I'm going to talk about is done at the console. You take a source, let's make it simple and say it's the lead singer. You can do a lot by sending a vocal to a sub group and then inserting a compressor. The more you push the fader the more it compresses, the more you push the group the more compressed audio you get. You usually work them in opposite directions so the volume stays about the same while increasing or decreasing the dynamic range of the performance. This one takes it a step further.
Take that same vocal channel and split it. You can use a Y-cable at the input, a mult in a patch bay, go from the direct out to the line in on an adjacent channel, or use an active splitter. You leave one unaltered and insert a compressor on the other one. Settings can be adjusted to taste. I like to absolutely crush the signal, it works great on drums but I'll get to that later. Then you can use the compressed channel to fatten up the uncompressed one, or do it the other way around and use the uncompressed one to add a little crispness to the squeezed channel. It's less of a push/pull scenario like the first trick and more along the lines of picking which flavor you want to use and then use the other one to trick it out a little.
On drums I used to send them all to a sub group (or pair of them if it was a stereo mix) and compress them there. Then I'd also send the drum channels directly to the main mix. With a little push and pull you can get a nice, fat, compressed drum sound but still have the transients punch through. I'll usually warn against double busing but in the audio world you only follow the rules until you don't.
Till next time Brethren of the Knob and Fader...