I like whiteboards online and offline because they are a great way to share knowledge and ideas. Being restricted by just text really limits creativity and spontaneity. Sometimes a mind map or a drawing is the only way to really capture a concept.

Here a few options:

Imagination cubed

http://imagination3.com/

I like this on because it is clean and simple. You can create and email on to others who can then make additions.

Check out this one I made.

The only thing is you can not embed the imagination cubed whiteboards

Sketchcast

There was a website www.sketchcast.com that allowed you to draw and it would capture it and make it embedable. A bit like a youtube for sketching. It was cool. The site was down when i wrote this lesson. I hope this doesn't mean the site is no more.

The alternative and originator of the sketchcast is here by Richar Ziade http://sketch.basement.org/2007/07/how_to_sketchcast.html . Basically film using a screen video captur tool like camtasia or captivate etc and then convert to upload to Youtube.

Others

There a probably a few other whiteboards out there. Add any you know of in the comments and I will update te lesson with a list.

Online whiteboards:

http://www.skrbl.com/

NOTE: It is so much easier to use a white board with a tablet pen or at least a mouse. I found it hard to use with a notebook touchpad. I ended up writing like a toddler.