This is a great write-up by Randy Oliver regarding the new Mite Away Quick Strips to treat for Varroa in the hive. http://scientificbeekeeping.com/an-early-summer-test-of-mite-away-quick-strips/
I have been using Api Life Var with pretty good success, which is concentrated essential oils (mostly Thymol), but I am really excited about the prospects of only applying treatment for 7 days instead of 21 one days.
MAQS is formic acid, which naturally occurs in honey. The product has recently been approved for use in organic hives by the USDA: http://www.regulations.gov/#!documentDetail;D=AMS-NOP-11-0058-0027
I just ordered some for spring and will post my results as time progresses.