three basic choices for doing digital macro work. as with standard photography, technique is everything.
1. best and most expensive is a dedicated setup like KevinL's with real macro lens.
2. next up is focusing closest your digital camera will allow, then use digital zoom to max setting. or shoot at highest resolution then digitally crop. either way achieves same results. prefer doing the crop in camera VS photoshop or other software.
3. last is a combo of #2 and addition of external len(s). My favorite is a jewler's magnifier/light combo. you basically place the magnifier/light directly over object to be shot. then shoot directly over large lens. you can also experiement with multiple lens.
results are not as good as dedicated setup, but aceptable. here's a pic of Li14430's two stage head and a wx1s using two lens.