If you have an interest in MacFamilyTree and have tried the demo, MacUpdate Promo, which is a site that runs daily and weekly specials on Mac OS X software happens to be featuring this Mac genealogy application for 50% off of the normal of $49, for a total of $24.50 US. The offer expires Sunday night.
It looks like there is an 8-day extended discount price of $39.20 if you pass on buying it this weekend.
Link: MacUpdate Promo – MacFamilyTree 6
MacFamilyTree 6 does require Mac OS X 10.5 or later.