I recently found out that DistroWatch has been running a monthly donation program since 2004 (that's 8 years ago). They put an advertising page in which users/readers/contributors can donate to them using PayPal or Credit Cards or buy an advertisement space and then DistroWatch will pick one of the projects every month and use the money they received to give donations to.
Well, in the last donation program, Slackware Linux gets selected and received USD 500 in cash. So far, it's the highest paid donation ever made by Distrowatch along with Gentoo Linux, Blender, and MythDora.
Again, congratulations to Slackware Linux and also to Patrick Volkerding himself as the BDFL at Slackware