I have a new toy, a Raynox DCR-250 super macro conversion lens. It is a cheap alternative to a macro lens but I am actually using it to get even closer than my macro lens. It clips onto my 100mm macro to let me get super close.
Depth of field at these sorts of magnifications is ridiculously thin and to get the most out of it you need a tripod and flash. So I doubt it will be an oft-used piece of kit for my favourite genre, natural light bug macros outdoors.
Still, it did give me a lot of fun yesterday afternoon putting it through its paces trying to capture something of the very smallest critters in my garden. The red-eyed fly below is smaller than an aphid.