Personally, I wouldn't put anything on the master bus until the VERY end, once your mix is done and there's nothing left to do. This is more or less to make it loud enough without a professional master, but if you limit it while you mix, and then take it off - your mix will sound different, and this fucks with the mastering engineer. If you don't ever plan to master the track then I guess its fine, kind of a matter of principle though, you never mess with the master bus until the end.
But alex and I might disagree on this :P
In the end, do whatever works for you.
The video I posted in the "dynamics in house music" thread is an example of abusing a limiter; essentially it does the same thing as a compressor by reducing the dynamics, but it doesn't reduce dynamics by a ratio, but an absolute ceiling. So any signal that exceeds the threshold on a limiter will only be as loud as the threshold. This is how you make your track a sausage, so to speak; limit it like hell, hope it sounds good. So if your track sits around -12 db but goes as high as -8 and as low as -10, you could put the limiter threshold at -12, crank the volume up a bit, and make your track really loud and sausaged, Then you can bring it as close to 0dB as you want, because you won't have any peaks that will clip; the limiter removes those peaks.
Hope that made sense, you can find information on this all over the place. I suggest you take a drum track or synth track and play with the settings on the limiter, and see what happens with different settings.
You can also use this to make absolutely MASSIVE kicks, but you need to be really careful with your settings. If you look at certain people's kicks the transient looks like its brickwalled. This is limiting in action.