Thinkature: Real Time Web Collaboration

http://www.thinkature.com/about/

Simple collaborative space that can be shared in real time. Free

With Thinkature, you can create a collaborative workspace and invite coworkers, friends, and colleagues to join you in just seconds. Once inside your workspace, you can communicate by chatting, drawing, creating cards, and adding content from around the Internet. It's all synchronous, too - no need to hit reload or get an editing lock.