Considering that many South Floridians wisely take advantage of the environmental niceties our climate offers -- at swimming pools and in convertibles, for instance -- you'd think outdoor music venues would be on durn near every street corner. They aren't. But there are a few choices. For an experience that can be duplicated at any massive, corporate-monikered shed in the country, you can make the journey to MARS in far west West Palm Beach. Or you can choose to investigate downtown Pompano's wonderfully intimate and unpretentious outdoor theater, which recently hosted performances by Cake, Tenacious D., the Cult, and String Cheese Incident. The venue could very well be expanded and start booking acts on a more regular basis, but then someone would have to move the bedrooms of this bedroom community -- which are so close that shows here must begin and end quite early. You know, come to think of it, this place is perfect just the way it is.