Mixin is a very pretty and simplistic scheduling tool that makes your calendar readily available to others. It's been designed to help you block out time and keep everything organized with color coding and an entry system that makes creating a new event as easy as typing just a few characters.
Like Twitter it centers around a blank box on the top of the screen where you can drop in text, along with a timeline of what's on your plate for the next five days. To create a new plan or item you can simply jot down what you want using conversational text, so writing "grab a beer at Dave's pub at 6" will convert that to a recognizable event that goes in your schedule. You can also accomplish the same thing by typing "Beer@Dave's 6."
The system rewards advanced users fewer keystrokes by learning some basic shortcuts, but those looking to create a more detailed entry can toggle an advanced view that lets you pop in things like addresses, specific times, and RSVP options.
Right after you make an event anyone who has subscribed to you will be alerted, and depending on their notification settings that means they could be getting real-time updates by SMS or a simple e-mail. From there users can interact with the event like they would on Facebook or Upcoming to make time or location suggestions, add photos and videos, or leave a note to explain why they're not going.
One thing to note up front is that Mixin doesn't sync up with Microsoft Exchange or any other calendar data feeds. Instead, you must include email@example.com as a guest when creating or planning to attend an event in any calendaring tool you're using and it will parse that data and convert it into an event on your Mixin calendar. It's not a perfect system, but if you're not worried about two-way sync this is a viable solution.
I'm still a little wary to recommend Mixin to the the casual user. As a standalone tool it offers little in the way of organization compared to most calendaring tools. Where it shines, however, is the social integration with other Mixin users. Like tools that help find a consensus for a single meeting time, Mixin does something similar with your social or work life. If you and your friends are willing to hunker down and log your schedules onto Mixin's servers there's a lot of power here, however I think Google's Calendar service is far easier for basic scheduling and appointments. It also includes daily and monthly views, which I think are a must-have.