I always find it interesting that the Linux people pay the most. Then again, the games are probably most impressive compared to games generally available on Linux, and least impressive compared to those available for windows. Not to say anything about the quality of three games, just commentary on the different gaming markets.
That's why I usually pay out a minimum of $20 for the bundle with 100% towards developers.
I may sound like an ass saying this but those are popular charities and receive a lot of funding from lots of resources, they can survive without my $5 or $10 while many of these developer groups have only released a couple games. I want to see DRM free indie game development take off so I will contribute to the developers who I feel need it more.
It's also a possibility that those that pay below average amounts are likely to signal their contribution being made under Windows. Alternatively, high payers have a higher likelihood of marking Linux.
