In the beginning Black Castle charged money for software. To accomodate this an online store was opened via a third party company.
Then Black Castle removed the price tags and started giving away the software for free. The online store was repurposed for accepting donations.
Then the third party company decided to delete all traces of Black Castle's store without explaination and evaporated like a cloud of vapor into the air.
Now you can donate to Black Castle by using either Bit Coins or Dwolla. Once you have Bit Coins you can donate any amount, even only a bitcent with no more than the click of a mouse. If you are unfamiliar with Bit Coins then you will want to start here and learn about this exciting new currency.