StumbleUpon is a great way to discover new and popular pages on the Internet: with the press of a button, StumbleUpon will load a random page tailored to your interests. It works well on desktop platforms, but the apps have a few tweaks to aid in the slightly different experience that come with mobile browsing.
The interface isn't unlike the desktop version; you have a web browser with an added toolbar from which you can "stumble" upon random pages, vote them up or down, and share them via social networks. However, due to slower loading times on mobile devices, the app adds thumbnail previews when you click the Stumble button so you can decide whether you're interested or not before loading the full page. You can also choose to stumble photos, Flickr, News or YouTube from the home page of the app, which is handy. All in all, it stays pretty true to the StumbleUpon experience, so fans of the site should definitely check it out.
StumbleUpon is a free download for iOS and Android 2.1+ devices, available in the App Store and Market, respectively. Unlike the site, you do need an account with StumbleUpon to use it, though if you don't have one, you can sign up right from the front page of the app.