Many cable companies are using iPad as a way to build a better navigation system, there’s one app that’s trying to build TV-like navigation for web videos. Nowbox, which is available as a free download on the Apple App Store, has succeeded in letting viewers surf through channels of web video on the iPad in the same way they would click through channels on their TVs.

You can set it up,by specifing categories of entertainment that are of interest to you, then link your YouTube, Facebook and Twitter accounts. Once that’s done,a TV guide-like navigation pane that will look familiar to anyone who’s ever seen a cable channel guide. All of which is the point — Nowbox demystifies the online video experience by serving up channels in the same way most viewers are already used to seeing them.

In this app Users are served up a continuous stream of videos, making online video viewing more akin to the type of non-stop stream they’re used to seeing when watching regular TV. Users can swipe back and forth through videos on a particular channel, and since Nowbox pre-caches those videos, they play pretty much instantaneously. Users can star videos as favorites, save them for later or share with friends and followers on social networks.

With more than half a million video views under its belt in less than two months since launch, Nowbox is expanding the app’s feature set to make it even easier to discover new content. For one thing, Nowbox has added a channel of video recommendations based on the categories of content that users signed up for. It’s also added an indicator to highlight new videos as they appear in a user’s channel lineup.

Nowbox is just one of many apps focused on improving discovery of streaming video on the iPad. Other competitors include apps like Showyou, Squrl and the Boxee iPad app. The hope is that Nowbox’s unique channel guide approach, as well as its new features, will extend the play time that users spend with the app. Nowbox founder Thomas Pun says thatUsers spend 18 minutes with the app per session on average.