An online "Chalkboard"

Hi, I'm a new user and I've been asked by someone to help them find a program or app online that is able to:

- Allow users to write on the UI, much like you would write with a pen on paper, or with chalk on a chalkboard

- Allow users to type on the UI as well, while never being restricted to typing alone

- Can be used alongside programs like Skype, Google hangouts, and other online tools for video cahts/conferences

- Preferably a program that can be used online and modified remotely by other users, as if they were all writing, typing, and modifying the same chalkboard.

I've3 looked into this myself, and have had little luck so far. It got bad enoug hto the point that I considered tryign to make the program myself (which isn't the worst thing, since I am trying to major in IT and programming), but in the interest of time, I'd figured I'd ask first: Does anyone here know of any apps or programs that meet most, if not all, of the above listed criteria? And if not, where would be the best place to start if I were required to make a program like this?

Any and all help is appreciated, thank you for taking the time to read this.