If you haven’t heard of MacHeist, then you should go check it out right now. It’s only good for four more days. What they do is sell a bundle for \$39 that includes lots of different mac software from different vendors.
They exact amount of software you’ll get depends on how many people sign up. As each milestone is met, another package is unlocked. 25% of the $39 goes to one of their 10 charities (or split between all 10), your choice.
So go and donate to charity and have a blast playing with all the software. ;-)