Last night in the Marketplace, a new app launched called Browser+ for $0.99. The app runs a modified shell over Mobile Internet Explorer adding new functionality to the browser not yet seen in the native app. That's a pretty significant addition as up to this point, it was unclear if this could be done in WP7.
Browser+ adds tabbed browsing like your desktop, in addition to an incognito mode for hiding web history and also quick access to the search bar (though with a dedicated search button, this seems less necessary). Overall the tabbed browser works just great--it's simple and intuitive as well as the incognito mode. Only downside is no landscape support, which is a serious drawback for some and hopefully something the developer may add in the future.
There is no try-before-you-buy here, so you have to drop $0.99 on it try give it a spin, but at that price, we think it's worth it.