Unchecky is a small tool that can help you prevent accidental acceptance of third party sponsor offers during software installations. The program runs as a background service and monitors your software installations. If it detects any unrelated offers, it automatically unchecks them for you, so you don't accidentally install any unwanted software.
We tested Unchecky with a handful of different installers and it worked particularly well with OpenCandy, AVG and some others (see our screenshots). Keep in mind that there are many different types of third party offers and installation schemes and Unchecky will not work with all of them - it missed a few during our tests.