We stream video: you can use a Flash media server (costs a lot of money), Wowza media server (costs less money), or red5 (open source) to stream. For images you can actually extract a bitmap from a frame of the video, which I imagine you can pass to JS and reassemble in canvas.

Is there any good documentation for setting up red5? My first attempt was a nightmare.

We just used Wowza, since they had an EC2 instance you could just boot up at a higher cost than a regular EC2 instance. The documentation is ok, not amazing, but getting it running is pretty trivial thanks to their examples.

You can use a developer's version of Wowza (the big limit is iPhone streaming is crippled).

A single license is like $1000, but you can instead pay by month ($60, IIRC).

Wowza also has a deal with Amazon, so you can run Wowza on EC2 and only pay by the hour (Wowza licensing included).