Internet services are often about providing you with online services.
Mixin is bringing some innovation there in the sense this is an online service to do real life things.

To make it simple, the concept is the following. Organise your real life activities online, allowing people to use their favorite tools and interact with you as they like. The example will be clearer.

Imagine you are heading toward a very rainy weekend and do not feel like staying at home. By indicating in your online agenda your wishes and free time, you allow them to make suggestions, propositions to get your activities planned. Feeling like a movie, add a trailer, share timetables, exchange views...you can do what you like. What is really cool too, is that you can also add info by the means you like : SMS, mail, IM, twitter... Whatever you say or sahre via any of these tool, automatically creates your agenda, giving your friends indications.

The early alpha of the product is about to open. I suggest you have a look at their site and ask for an alpha account.

If you would like to see it, here is the mixin presentation.