racketman: Hi Alacher, lots of great macro work is done without flashes, indeed I would argue you can't beat natural light. You will often need a low level tripod of course and a Plamp (Plant clamp )is very useful. Stacking software will let you use wider apertures and still get good DOF when required.On Flickr check out the work of John Hallmen.
Right, Stephen. Another plus point for flash is that you can shoot anytime you want. I do a lot of night macro and you can forget about natural light at night :D
I agree with you there, John. Try photographing a Camponotus gigas running away from head decapitating Phorid flies.
Having said that, I do love natural light shots too! Anyone who's doing just one and not the other is missing a whole lot!