Looking for shared, extendable Whiteboard plugin in browser

Hi all,

I am building a network application which will enable peer to peer
communication.The application is build using ruby on rails.

I am attempting to build a white board which will allow simultaneous
and syncronous developing and editing of Images.

I tried adobe SVG pluggin and other network image generation tools.I
need to integrate these tools with my ruby applications. my problems
are

1. How do I display applications written in c++/java script in the
browser
2. Adobe SVG pluggin is a exe. How do I render it in the browser and
syncronize the building of images on the network
3. Are there some other applications or pluggins which I can integrate
with ruby on rails and
implement this shared white board in my application


Thanks
Sapna