Spy! As in "Spyware"?
I have two programs, that I've used for years, to keep the spyware down to a minimum.
The first program, "Spyware Blaster" works with the Hosts file to passively block spyware.
It's free, and only requires the operator to update it once every week or so.
I like programs that are simple, and FREE!
The next program "Super Anti Spyware" is a more Active program that will find and remove both Tracking Cookies, and Trojans as well. I actually enjoy running the updates and scans with "SAS" so I just use the FREE version. If I wanted SAS to get its own updates and run its own scans, automatically, I'd have to buy the program.
But I get the protection I want for FREE, so why waste my money?
I was doing a PC tune-up for a neighbor one day, and I installed and ran SAS, for the first time ever, on that PC, and it found and removed just over 140,000 Tracking Cookies! Yikes! I left the program there, and showed them how to run it.