InvisibleHand is now available as a Safari extension. It lacks a few bells and whistles but otherwise should work just like other version for Chrome, Firefox and Internet Explorer. Please let us know if you notice anything unusual!
InvisibleHand Blog
Watch this space for the latest news about InvisibleHand project. We'll blog here about new retailers, new countries and new features.
[...] The InvisibleHand extension will subtly let you know when it finds a cheaper price to a product elsewhere on the Internet. The list of supported retailers is fairly decent for the U.S., UK and Germany, but more are being added frequently. [...]
it’s not showing on the menu bar after I downloaded it (twice, the first time it just disappeared from the extensions bar, but the second time around it;s still there installed but I can’t open it)
InvisibleHand dosn’t have any menu bar. It is invisible until it finds a product that matches your search, and then shows you a notification!