You know, ever since I've given up on the idea of mastering/learning to master, my mixes have actually improved dramatically
The only mastering-related thing I do is to bounce a version of the mix w/ a limiter for myself and to do some basic trimming and fades. But I try to get the mix itself as close to a final product as I can.
As for "gluing", it's something that's often accomplished during the mixing process. Personally, I like to mix through buss compression right from the start. Adding buss compression towards the end seems counter intuitive to me.
As a result, I use less compression on individual tracks. I'm a big fan of stage compression - it seems to help me get the benefits of compression w/o the adverse side-effects.
As Jeff mentioned, try to stick to low ratios - I never use anything above 2.1:1. Attack between 4 and 10 ms for starters. Release, depending on the material, but I seem to like my usual compressor set for auto release based on a value of 580 ms.
Usually, the buss compression barely shaves off a few db's here and there - 2 or 3 at most.
As for plug-ins for that task, well, I'm sure you'll find lots of people praising this or that one. I do own a couple of nice ones like Waves and McDSP and some SSL clones, but at the end of the day, 99% of the time, I just use the one that comes bundled w/ my DAW, in VCA mode.
My second choice would probably be Waves Renaissance Compressor - that's right, even before dedicated buss compression models. Because I know it so well.
If I start fiddling around and switching compressors and agonizing over how one seems to be better than the other and to magically improve the mix, chances are that the mix has a more serious problem than the buss compression.