When you're reviewing a commercial web site when shopping for a product, such as airline tickets, rental cars, or even dog food, InvisibleHand will let you know if you can buy the product more cheaply at other sources and link to them. We snapped the screen shot below to show what the discreet prompt looks like when it finds a lower price, which appears at the top of the browser window:
We've only been test driving it for a little while, but our initial impression is that the app is pretty cool! The app is free and versions are also available for the Firefox, Safari and Internet Explorer web browsers from InvisibleHand's web site.
Elsewhere on the Web
Carolyn Nicander Mohr offers a positive review of the InvisibleHand app.
C|net's Rafe Needleman reconsiders his initial positive review for the app based upon privacy issues related to cross-site data leakage, where his search for a product on one site was unknowingly communicated to Amazon's site.