Imagine for a second that you go into your favorite restaurant and find a completely new soda dispenser machine. Not that old one you are used to, but a completely brand-new design which is plugged into the web. At first, it looks a bit futuristic, it doesn't have any triggers to pull your favorite soda, but instead a large touch screen.
From the screen, you can select one of three options:
1) Create your own personalized soda/juice mix:
Will take you to a menu where you can select exactly which percentage you want (let's say, in increments of 5%) of each ingredient. There are probably about 10 or 15 different ingredients. So, to illustrate, something in the lines of: give me 15% of this cola, 15% of this other one, 50% orange juice and 20% mango juice. Once you are done, the machine will prepare your mix, but will also let you save it under a nickname of your choice. So you can type in this is my "Seb01" mix. The machine will give you back a ticket with a number that uniquely identifies yourselve.
You can later go to a social 2.0-ish website where you can login with that number and see how "Seb01" is doing. You can link it to your profile and write your own comments about it. You can link your profile to your personal blog or myspace address. Other people can order a "Seb01" from any of the machines in the "web" of cool restaurants and places having this new kind of machines. You can tell your friends to try it out, and you could "perfect" it little by little (Seb02, ...) They can also login into the website and post comments or recommend your "Seb01" drink to their friends, and they can also see the components inside "Seb01" (so they can experiment with variations of their own).
2) Select from most popular mixes:
You will get a menu with the 10 most popular mixes. Mixes get more and more popular depending on how many people drink them, how many people read about them on the site, post a comment about them, "digg" or "dugg" them, you-get-the-point. You also have a place where you can type "Seb01", even if it is not the most popular one, you can still order it if you've heard about it!. There might also be a menu with the less popular ones, the most exotic ones ("different" ones), etc.
3) Select from the existing "boring" commercial mixes:
Here you can get your boring 100-years old mix that has been there forever. Or may be you can also find new ones being pushed by known brands so that you can try them out.
There are a few more twists:
a) All personalized mixes formulas are in the public domain (exept may be for some of their ingredients from the machine). The company having these machines could also commercialize your popular creation in cans, etc without owing you any royalties or license fees, but you could also do exactly the same.
b) If you get to author a popular mix, the company will give you some incentives, gift, or may be hire you! 
c) The social site could also collect some ad-related revenues, subscription fees to extended services, etc.
OK... I'm running out of ideas right now. It seems to me this would be really cool, but mostly for kids and teenagers. Some adults may also enjoy it.
Another twist: The futuristic bar. Where you can sit down and have your display on what you want to mix in your own cocktail (alcoholic or not), and everybody can also see on their displays what everyone else is mixing and drinking ... you can also enter your profile (...), save it, etc. There could be a "web" of these futuristic bars, where again the same ideas apply: a social 2.0-ish website puts them together and creates a world-wide phenomen... You can send IM messages to other people if they are in another bar, or you can just go talk with the people there... so many possibilities... The site also has videos from different bars and locators to other bars in the "web", should it happen that you are travelling.
I'll post this one on the Entrepreneurship category. Simply because I believe these are particular examples of some broader, more general ideas behind it...