PlaceTime.com is intended to be a URI space containing URIs that represent places and times.These URIs can serve as common identifiers for a wide variety of applications such as genealogical research or calendaring.
A tweetdoc is a document that brings together all the tweets from a particular event or search term. A tweetdoc allows you to keep a record of an event through twitter.
Eventseer keeps track of events, people, topics and organizations. When you sign up you will get a personal tracker that can be customized to your liking. If you are interested in a certain topic then you add it to your tracker. If there's an academic that works on something that interests you then you add that person.