In an effort to greatly increase the snap, liveliness, and initial crack in my drums I often use parallel compression. The idea is to send the signal from snare top, snare bottom, and sometimes kick drum to a compressor via an aux send. Then, I solo that compressor and adjust the settings so that the compressor is very aggressive (threshold -40dB or so, ratio set to infinity). From there I play with the attack and release times. The idea is to let just the initial crack through the compressor and smash everything else. I prefer a long release time (maybe around half a second) give or take.

The real secret to making this work is how you set the attack time. Try setting the attack time as fast as the compressor will go. Then try setting the attack time at something like 500ms. The tone will be DRASTICALLY different. The fast attack time will completely knock off the attack while the 500ms attack time will let a ton of it through. I usually end up with the attack settings somewhere in between 2-10ms.

While I've done this with numerous compressor plugins, I find that the Kjaerhus Compressor (a VST plugin) seams to be the most aggressive plugin I've used for this. I love the almost violent crack I can squeeze out of my kick and snare drum. When compared to the Waves Rcomp, the Kjaerhus Compressor seams 10x more aggressive (which is exactly what I want in this case).

While the Kjaerhus Compressor seams to be a good overall compressor, I think it really shines on parallel compression on drums. Since it's a free plugin, I give this plugin the official Infinite Value Award.