To complement Live Search Cashback, the program that pays shoppers to search for products using live.com, there now comes another incentives program from the Live Search team: Live Search Perks. With this new program, available in the U.S. only, you simply download a program to your computer which tracks how many times you use Live Search. The program doesn’t track what you’re searching or any other info about your search habits, only when you use Live Search. As you search, you’re given “tickets” for using Live Search which can then be redeemed for prizes. Those prizes aren’t too shabby either: 525 tickets gets you 5 free music downloads; 1800 gets you 1,000 free air miles. You can also choose to donate your tickets to charity, if you would like. The program is being limited to the first 250,000 users who sign up through December 31. The program ends April 15, 2009.
Plus - You get 500 tickets just for signing up!
Here is a screen shot of what it looks like in your browser:

Also, it's worth noting that you must use IE 6 or higher to install the Search Perks toolbar.
search perks