At this point in time there are many user interfaces for searching, browsing, and watching videos on YouTube. Apple's got custom interfaces on both the iPhone and iPod touch, along with the Apple TV, while YouTube's got its own mobile frontend that works pretty well, but lacks some of the polish of Apple's efforts. One of the newer companies trying to improve on YouTube's offerings is 3rd Eye Solutions which has an app called iDesktop.tv (formerly known as "YouTube Desktop"), that lets you browse, view, and search YouTube videos in a similar style to a desktop application.
The service is a little reminiscent of Apple's iPhoto, mainly due to an array of video thumbnails that can be re-sized on the fly with a little scaler in the bottom corner of the screen. It's also got a built-in search tool that makes it far easier to sort through the often dizzying amount of results that you find clumped together in YouTube's less than stellar site search. This is, in fact, one of the most standout features of the app, since the company has one upped YouTube's own method of digging through what's become a huge repository of content.
There are also some other nice tweaks, like a resizing tool that lets you adjust a video to just the right size, as opposed to the all-or-nothing, full-screen option that comes stock with YouTube. Break.com's video player has had this feature for quite some time now, and I think it's really handy.
What really makes the service worth coming back to, however, are the video downloading tools. If you're a registered user, you can download the full version of any YouTube video in a variety of formats, both for popular portable devices and as a Windows executable file that will play on any computer running Windows. Be forewarned though--you're limited to 10 downloads a month, which is hardly conservative for most people's needs, but heavy users will be likely to reach their limit quickly. This would normally be a huge hindrance, but there are a ton of free YouTube video downloading tools out there, including the latest version of RealPlayer, along with Web and services like VideoDownloadX, Zamzar, Hey!Watch, and KeepVidthat take the edge off.
This tool is definitely worth giving a look. While it may not be as powerful as some of the big video search aggregators like Truveo and Blinkx, which pull in content from all over the place, the viewing experience is far more enjoyable romp through YouTube's offerings. I expect them to expand into other hosted video services in the future, which could make it even more useful.