Are there any chat room like services where you can use a pencil/marker tool to draw at the same time?

I have a tricky math problem and I want to conference with a classmate. The only thing is, it is a Calculaus Volume problem, and it has a diagram. It is really hard to explain my steps over the phone, so is there a chat service or something like it that allows for some sort of drawing or sketching tool at the same time so I can draw out my steps?

Check out inklink @ http://www.shockwave.com/contentPlay/sho...

It is a chat/charades room, in your circumstances choose a room with no one in it but you and your friend, otherwise other people would be drawing also.
You also get to use different colored markers too.
The nice thing is that if an uninvited person comes in your room you can boot them out.

Isketch.com is pretty cool too, its also a drawing site, but it does have some chat-only rooms to that can be customized by you. Its pretty neat. Report It

msn messenger has a drawing tool, and it also has a grid of graphs

yahoo messenger (and chat i think) has an IMVironment called Doodle. you can draw there show your illustration to your chat mate. me and my supervisor sometimes use it if we cant figure things out when just chatting. it gives you the picture you want to tell your chat mate. try it its fun..