First things first, Yoono is an extension currently running on FireFox. While there is an IE version in the works (and a FF3 version), right now you'll need to be running FireFox 2 to play around with Yoono. As I stated before, I currently use Flock, which is a FireFox 2 derivative, so most FF extensions work just fine, although there are unintended consequences from time-to-time, as is the case with Flock.

Now to the nitty gritty good stuff! Yoono has a TON of features. I'm not exaggerating when I say that this may be the most well rounded extension I've seen in a very long time. It's going to be a challenge for them, however. Most people already have extensions to take care of many of the features of Yoono: RSS readers are plentiful, Stumble Upon like recommendations are all over the place, social bookmarking tools are too numerous to name. What is going to set Yoono apart is how smoothly these are all integrated with the other features, and how slickly this extension fits into your browser. But those tools aren't really the strength of Yoono, in my opinion. It's true strength is the Discovery functions of the extension.

Yoono provides immediate suggestions for other websites, photos and videos to you based on what your currently viewing. The process works similar to the "if you liked this, then try this" method of Amazon or iTunes, and seems to be pretty decent thus far. The recommendations are based off of other Yoono users though, not key words and such, so because the service is in closed beta, there are still a good chunk of sites that return no results (Homotron, for example). The photo and video Discovery modules work the same way, which provided an interesting twist to the formula. This is the real "power" of Yoono, though, so this is where they are putting a lot of development emphasis at the moment. This is actually pretty nice, but the only problem I've seen so far is that it doesn't integrate with your other bookmarking sites like Del.icio.us or Stumble Upon.

Yoono also provides a browsing clipboard for you to save any pictures, videos or sites that your browsing for later use, which comes in handy for blogging. This is another feature already integrated into Flock, however, I think I prefer Yoono's clipboard. It looks cleaner and is more integrated, even if it's just not as strong overall.

In taking another nod from Flock, Yoono provides blog publishing directly from your sidebar. Unfortunately, I haven't tried this out just yet. Honestly, my personal blog has seen a drastic decline in publishing since taking on writing duties for Homotron, so while this could be a great tool, I just haven't found occasion to use it just yet.

Finally, one of the niftiest features is the YouTube integration. For YouTube newbies, this is fantastic, and for YouTube experts, this is a refreshing way to approach your favorite video sharing site. In the YouTube module, you can select from a vast array of search filters to highest rated, highest rated today, recently viewed, recently added, most viewed, etc., or just do a plain old search. The search returns results very smoothly and quickly (It's nice to see a good use of that YouTube API). My personal favorite piece of the YouTube module is actually how the videos playback. A shadow screen is overlaid on top of your current screen and plays the video. You can vote for or against the video as good or bad, or just say its funny. What's great is that whatever you are currently browsing is not disturbed by the whole experience.

The are a few other bells and whistles that come with Yoono and I'll go into greater detail when the official release comes out (In theory, that's later this year). In general, if you can get an invite, and these features sound exciting to you, I'd say give it a shot. There are many bugs to fix still, not the least of which being the poor integration off all the modules with each other (If I recommend a video, it posts the link to that video as a Facebook status and a Twitter... but the links don't really work. I'd much prefer a "... recommends this video" thing in my friend feed instead of my status changing), but what's there is nice and well developed. I'm still leaning toward using Flock if you want a well developed and thoroughly thought through Social Media platform, but if the kinks in Yoono get ironed out, (and a release candidate comes out for FF3), I may be making the move back to good ol' FireFox!