I picked up a 52mm/58mm reversal ring to have a quick play (£5, so not going to break the bank). First impressions are that it's very hard to get right but it should be possible to get some nice shots. The DOF is almost no existent.
Blade of grass - 6s, f/11, ISO 200
Fly wing (not very good) - 6s, f/11, ISO 200
Flower (4mm across shown in this pic) - 8s, f/11, ISO 200
The setup
Unless you have a few flashes you can set up externally and some very cooperative insects you won't get shots of anything like that unfortunately, fun thing to try if you haven't got the money for a dedicated Macro lens though.
Blade of grass - 6s, f/11, ISO 200
Fly wing (not very good) - 6s, f/11, ISO 200
Flower (4mm across shown in this pic) - 8s, f/11, ISO 200
The setup
Unless you have a few flashes you can set up externally and some very cooperative insects you won't get shots of anything like that unfortunately, fun thing to try if you haven't got the money for a dedicated Macro lens though.