Internet Explorer vesrion 8 has this neat feature of surfing anonymously by switching to Inprivate browsing. This allows the users to supress cookies and other user identifications. Very useful if you browse on your friends computer , school or at a library. With little effort we can clear off history from internt option dialog but Inprivate let you keep the old history and only current browsing is cached.
Surana blogger writes how Inprivate browsing helped him find $200 difference in flight tickets through Orbitz via Inprivate browsing. Here is the link. Its intersting to see why Orbitz is giving a deal price to non registerd users. Probably to attract non customers to its site and then burden them with different deals.
If you use IE8 then using Inprivate browsing help you not only in identity gaurding but also sweet deals like the one found above.