1. UC Browser
Taking a cue from Opera, UC browser makes use of compression to deliver a good browsing experience. Features include Incognito (private) browsing, personalized wallpapers, a download manager, and full screen view. The latest version (which is 2.7.0.223 as of this writing) is 6 MBs to download and is available on both Windows Phone 7.5 as well as Windows Phone 8.
The browser handles downloaded images, audio and video with the corresponding applications in Windows Phone appropriately and also supports rotation lock, which means that the orientation of the UI can be chosen to be locked in order to prevent unwanted automatic UI switching between portrait/landscape modes, when the phone's physical orientation changes.
2. QuickSurf Browser
Simplicity goes overboard in QuickSurf Browser, which is a browser without many bells and whistles. It offers a very basic browsing interface and a pre-defined speed dial grid of popular websites. Besides that, the browser doesn't have much to talk of. A poor choice of background and font colours give a low score on aesthetics.
Given it's basic features, it is no surprise that the latest version (which is 1.0.0.0 as of this writing) is less than 1 MB to download. QuickSurf Browser too is available on both Windows Phone 7.5 as well as Windows Phone 8.
3. Beyond Browser
Built on top of IE, Beyond Browser offers tabbed browsing and a few other features such as history, image saving, etc. which puts it between UC browser and QuickSurf Browser as far as being feature-rich is concerned. Page transitions are pretty quick in Beyond Browser. The latest version is 1.0.0.0 as of the time of writing and is 2 MBs to download. This too is available for both Windows Phone 7.5 and Windows Phone 8.
4. Surfcube 3D Browser
In Surfcube, interaction with the browser happens in a cube-like environment, hence the term 3D. It is fun to swipe between different screens of the cube. The browser supports sharing of links to various social networks and also supports rotation lock like UC browser. At the time of writing, version 4.3.0.0 is the latest (which is about 1 MB to download) and is available for both Windows Phone 7.5 and Windows Phone 8.
5. Incognito Browser
This a simple web browser that claims to cover your tracks by not keeping any browsing history. You can still save your favorite websites though and protect them with a password. Beyond that, the browser offers little beyond what QuickSurf scores on the functionality front and doesn't support tabs. Version 2.0.0.0 is the latest as of this writing, which is 2 MBs to download and is available for both Windows Phone 7.5 and Windows Phone 8.
6. Private Browser
This is another privacy-focused browser that is available for both Windows Phone 7.5 and Windows Phone 8. It supports features like full screen browsing, portrait / landscape orientations and search from within the address bar. The design of the menu elements seem to have been inspired from UC browser. Version 1.1.0.0 is the latest as we write this, and is less than 1 MB to download. Private Browser too supports both Windows Phone 7.5 and Windows Phone 8.