I've written before about the Hover adjustment in the Appearance/Edit Shape/Body sliders, and how it can be used to get your feet up out of the floor, or down to the ground.
But as you probably know, the Hover slider has two big drawbacks. One, its adjustments are too coarse. Even a one-number change can leave you either floating, or embedded. And two, it doesn't work with No Modify shapes.
But the clever Nalates Urriah has come up with a workaround for this. It takes some effort, and two more attachments, and it's kludgy, but it works.
For the gory details, see her blog: http://blog.nalates.net/2013/05/21/second-life-hover/