For the aspiring drummer, excellent time keeping is essential to your success. Traditionally, students were encouraged to purchase metronomes for practicing. Typically these metronomes were frustrating to use primarily because the volume of the metronome was never loud enough to hear clearly over the rhythms being played on the drums.
If you've never played drums while listening to a metronome, or if you are unsure of what a metronome is, I suggest you check out the online Metronome, via Metronome Online, a service of the EMusicInstitute. At the Metronome Online site, there are a few excellent articles about metronomes:
"A metronome is a practice tool that produces a steady pulse (or beat) to help musicians play rhythms accurately. The pulses are measured in beats-per-minute (BPM). Most metronomes are capable of playing beats from 35 to 250 BPM. Common uses of the metronome are helping you to maintain an established tempo while practicing, and learning difficult passages."
Though I think every musician should practice with a metronome, for drummers it's sometimes best to use a drum machine than to try and use one of the more "classic" ones that has traditionally been used.
I used to use an Alesis HR-16B as my metronome. I liked using a drum machine such as the Alesis HR-16B because I was able to turn the volume up loud enough to hear the beat over my drums and cymbals. I was also able to program different beats with different accents, such as putting a tambourine sound on the upbeat, while a clave or click held down the downbeats.
I have also used a "Dr. Beat" metronome which I tended to use more for getting tempos during a live performance or determining tempos during band rehearsals using the "tap tempo" function.
Below are a few metronome options for you to check out:
BOSS DR-880 Dr. Rhythm Drum Machine
KORG BeatLab Digital Metronome
The BOSS DR-880 is more of a typical drum machine, and so it is more expensive. The Korg BeatLab metronome is more similar to the BOSS DB-90. I think any of these three products would be an excellent "metronome" choice for the aspiring drummer.
Another option I should mention is the use of a music sequencing program such as Apple's GarageBand or Propellerhead's Reason as your metronome. These programs offer more functionality than a traditional metronome, and might make more sense if you are interested in programming, sequencing and recording your own music.
Regardless of the option you choose, keeping excellent time is important for every musician. Using a metronome or drum machine for practice can help you become a better "time-keeper" and thus a better musician.

