The MacHeist 4 bundle is an incredible deal. For just $29, you get Scrivener, Jurassic Park: The Game, DiskTools Pro, a year of Evernote Premium, and a bunch of other great stuff. Even if you only want one app, you'll probably still save money by buying the bundle.
Even better, 25% of the proceeds go to a number of great charities, or you can specify one from their list. If you need help deciding, Charity Navigator is a great guide, but they're all pretty good.
Buy this bundle, get an incredible deal, and help a worthy cause.