Surfy for Windows Phone 7 is a free, tabbed Web browser
Surfy offers tabbed browsing, a fullscreen mode, and orientation locking so that you don't unexpectedly switch from landscape to portrait viewing. Its address bar provides suggestions as you type, and autocomplete is supported for text input fields.
There's also detailed in-app help provided, and Surfy's developer is keen on adding new user-suggested features -- you can pitch your ideas using the app's feedback system.
Surfy is available for free from the Zune Marketplace.