Fills in passwords for you and shows you a lot of ads.
Upon visit of some Gator related pages, it tries to download and install. According to Tribune Media Services (via http://www.securitynewsportal.com/ via http://www.cexx.org/gator.htm): "Gator tracks the sites that users visit and forwards that data back to the company's servers. Gator sells the use of this information to advertisers who can purchase the opportunity to make ads pop up at certain moments, such as when specific words appear on a screen. It also lets companies launch a pop-up ad when users visit a competitor's Web site."
And Gator saves your identity in the HKEY_CLASSES_ROOT\CLSID section of the registry - good place to hide, if you've got something to hide.
Some information we may collect, use, and associate with your Anonymous ID includes:
Which web pages your computer views and how much time is spent at those sites
Your response to the ads we display
Standard web log information and system settings
What software is on your computer
Your first name, country, and five digit ZIP code
Your GAINware usage characteristics and preferences
Information associated with your Anonymous ID is used in any of three ways: a) to offer assistance (e.g. knowing when to offer help filling in a form or adjust your computer's clock), b) to select and deliver installation files for optional new GAINware and/or third party software applications, and c) to deliver advertisements and information to you on behalf of our advertisers who are often competitors of the web sites you are viewing.