Manfrotto do a 2 piece centre column that allows you to get down to ground level with most of their tripods and it's standard on some of their models. I've recently switched to the Gitzo range of tripods because they are more sturdy (but more expensive) This is my current macro rig, but I'm playing with a pair of flashguns mounted on brackets with homemade softbox diffusers at the moment to eliminate the odd lighting the ring flash gives with the Canon MP-E65 macro lens or Sigma 150mm macro. I use a manfrotto 3 way geared head and a micro positioning slide to get the views I want. It takes time to set up but the image detail is well worth losing alot of images.
