For those who don't know how Humble Bundle works, in this case, you would give a charitable donation (either to the default charity - Traveling Stories - or one of your own choosing!)
These comics are DRM free and come in multiple formats (such as CBZ and PDF.)
You pay whatever you want for these comics, unlocking more books as you go. $15 will get you ALL that are available -- which includes almost every Ghostbusters comic (excepting the TMNT crossover, RGB crossover, and RGB/Mars Attacks story!)
This even has the first five issues of current series Ghostbusters: International!
YOU CAN'T GO WRONG!
Other charities I can suggest? The Hero Initiative, Reading with Pictures, and the CBLDF -- these are all comic book related to one degree or another. There are medical research and philanthropic choices aplenty. Thousands of choices!
GET SOME COMICS, DO SOME GOOD, AND SPREAD THE WORD!
(And also hook some friends on the comics by me, Dan Schoening, and Luis Delgado! The more the merrier!)
Here's the link to the humble bundle -- HURRY! It only goes to June 14!