One of the joys of attending Macworld/iWorld is talking to new developers and discovering apps that you know are going to be "keepers." That's the story for me and Tappd (free) from Australian development shop Burst2Life.
So, how does this iPhone app work? Simple. You just install the app, log in using one of a number of social networks (I used Twitter), and then start playing with this gorgeous app. The home page of the app shows apps that are trending in interest from others. For example, when I looked at today's feed I noticed that Fantastical 2 for iPhone is hot, with 8 "Tapps" (recommendations from others) and a number of downloads.
You can recommend (Tapp) an app, giving your comments as to why you like it. Others see your recommendation and can also Tapp it and leave comments. And as more people agree that an app is "hot", it rises towards the top of the trending list. You can follow other users and see what apps they're enjoying, invite others to join Tappd, and more.
Don't like a particular category of app? Then don't add it to your list of interests. For myself, I started with navigation, photo & video, travel, utilities, and weather apps out of all of the available app categories. That way I'm not really going to be bothered by fashion apps, which I loathe since I'm a 56 year-old bald guy for whom blue jeans and a t-shirt are the height of fashion...
The UI is quite unique -- there are three main "panels" that you can swipe left or right on to navigate. The leftmost panel is for settings, the center panel shows whatever page you happen to be viewing at a specific point, and the far right panel is for searching for apps by location, app name, or location. When you swipe right or left, there's an origami-like "unfolding" animation that is just amazing.
While there still aren't a lot of users of Tappd, I think this app has a chance to become the app discovery tool of choice for a lot of people as it is easy to use, social, and just plain fun. It's free, so downloading it, give it a try, and see if you agree with me. Oh, and you can follow me on Tappd to see my personal recommendations.