Scott, I think Rowaphos is supposed to be one of the best and I know Elite had some, also PHOSar by Warner is supposed to be as good or better and has larger particles. Wais is supposed to carry it.
Phosguard is an aluminum oxide binder that can possibly release aluminum and irritate corals. See link
Rowa, Phosar, and Phosban are iron oxides that can possibly help with macroalgae growth but usually the phosphate reduction limits it.
Link to phosphate article.
http://reefkeeping.com/issues/2006-09/rhf/index.php#15