I usually just use the computer with a loop on record mode.

There are too many choices and they all basically do the same thing. Go to the music store and check them out. I would just go with price and a quality brand name.

Are you using a DAW or DAW software for a computer? If so does it have a click-track option and can your musicians play to that?

i guess you don't really need a seperate metronome, if you use a DAW with say logic or cubase or the like you have a clicktrack option, or you can create a simple loop, as mentioned. i use sometimes an old drum mashine. works well... but if you think you really need a standalone module, boss (sorry forgott the excact model no.) has a decent unit for around 40pounds UK with all the advanced settings, like tripplets and so on, also tama (the drum manufacturer!) has a nice unit, very very loud indeed and shit loads of options, also tripplets and if i remember right up to over 300bpm if you are into speed...
also korg does very cheap but more simple metronomes.

there are several software (mostly shareware!) metronomes around as well, check google... they mostly go around 10-20 bucks. like dr. bertotte for OSX for 10bucks.

thanks all

lots to think about
yes my DAW DP4.5 has a click track option, but it only sends the click out of my computer speaker.
it will also send a MIDI signal to an external drum module, as well.
Im thinking I might use Reason via re-wire and use either a loop OR the the drum machine.
cool.
joshua