itch.io - An online game marketplace and community.
GOG.com - DRM-free game store, selling both new and old titles. No clients required.
Humble Bundle - Buy a bundle of games, you decide the price, and support charity in the process.
GnuPlot - Gnuplot is a portable command-line driven interactive data and function plotting utility.
The Indie Gala - Buy a bundle of games, you decide the price, and support charity in the process.
Epic Games - Computer game storefront that gives 88% of revenue to developers