I'm a little late to the party but here is another suggestion: http://potree.org/
It's an open souce, WebGL based point cloud viewer I've been working on for quite a while.
== UPDATE ==
It can render large amounts of colored point clouds. LIDAR data without colors will be supported soon.
Potree is based on three.js which means, you can also do everything that three.js offers, like rendering meshes, splines, lights, shadows, etc.
== OLD ==
Here is a nice demo: http://potree.org/demo/pompei/pompei.html
And here is a showcase from pix4d using potree: http://pix4d.com/discover-interact-3d-pointclouds/
Source code is available at github: https://github.com/potree/potree
And currently I'm working on a rewrite from scratch as a three.js based project:
This rewrite will have to advantage, that you will be able to use everything three.js has to offer as well, once it's finished.