I keep recurring donations to big projects like KDE and one time once in a while to smaller projects/devs. There's no incentive for me to donate a dollar to someone who wrote an app to control the flash but a one time donation is good. One time donation is also good for projects you just check out and think it's good. Projects I heavily use also get a regular donation. And I didn't sit down and looked up every project but I star everything on github at first and then after a while I donate. A star is the minimum I do for good projects