Avoid to get unwanted applications while downloading on many websites with AntiAdware! (also known as Adware Atomizer)
Click on a screenshot to view it larger
See here for the full list of the ~40 supported websites.
or (not recommended)
After that you correctly prepared the installation, you can download the script here:
Check it out here! https://github.com/HandyUserscripts/AntiAdware/releases