If you've ever wanted to know what's happening with your web site as it's happening, you may want to take a look at real-time web site analytics provider Chartbeat. It's a new and very slick service that provides a rich set of real-time analytics. They offer a range of useful tools like their Real-time Dashboard (shown below), traffic alerts (ex: get an email if you've got an above average burst of site visitors), and their API (our chartbeat API Profile).
Nielsen, the media-measurement juggernaut, announced that it is opening up its API for the first time. Nielsen made the announcement alongside many other groundbreaking launches and promotions as SXSW continues to heat up. With coverage in more than 100 countries, Nielsen maintains a treasure trove of data that developers have long been eager to get their hands on. With the API release, developers can begin to build applications directly off data that is generated and maintained by Nielsen.