In this post, I will describe the setup that I use to record my drums while practicing. I recently bought a Zoom H4 Handy Recorder. It works really well, and I think it is a worthwhile piece of equipment. One of its really nice features is the ability to connect two external sound sources and also supply phantom power. The device allows individual level adjustment for each source, and will also mix the two inputs into stereo. I have it setup with a Tama Rhythm Watch RW105 metronome, and an omni condenser microphone. The mic is normally used for testing the frequency response of home theaters and it has an extremely flat response from 20Hz to 20kHz. This doesn't necessarily make it a great overhead mic for drums, but it's what I have.
The output of the H4 goes into earbuds, then I wear large earmuff-style hearing protectors over the buds. This lets me adjust the volume of the metronome and drum kit (from the single condenser mic) very easily. I can also hit record on the H4, and make a quick track so that I can critique my playing very quickly. This setup has proven very useful.