threex.js

Live edit of threex.js code, one of the first object oriented wrappers for Three.js library to see the live edit click here

One of the first 3D games in the browser.

Another amazing demo that uses Ammo.js for physics and CubicVR.js for the rest by Charles J. Cliffe

Very cool demo with Three.js of a NY city

Rather simple with objects, but interesting because of
the interaction demo of a NY city done with Three.js

Three.js development as easy as drag and drop.

Creating Three.js scenes by dragging necessary elements  by idflood.

According to the developer, it is an attempt to make something like "vvvv" in javascript, html and webgl.

vvvv is a hybrid graphical/textual programming environment for easy prototyping and development. 

Ammo.js, Three.js are we ready for games in the WebGL enabled browser

Rag doll Demo with three.js and ammo.js by Steffe. It is a great demo of what could be done in the browser with real world physics simulation provided by Ammo.js and 3D scene/ object representation handled by Three.js

Steffe also made an interesting analyzes of   the performance test of ammo.js with three.js.

Terrain generation: the diamond-square algorithm and Three.js by Sann-Remy Chea

An impressive use of a diamond-square algorithm with WebGL and Three.js. Could be used in game development. Shows good performance. In the demo you can change some parameters.
DEMO of Random terrain generator

Physics with Ammo.js + Three.js by Chandler Prall

A very good guide for beginners in Ammo.js programming. Ammo.js is a JavaScript based physics engine build from Bullet (physics engine written in C++)

Interesting post, good description, but with all respect to the author the demo is not so interactive (which is main advantage of 3D :)

For some reason the demo with falling boxes crashes on my browser after like 10 seconds.
Edited: It is not crashing anymore, I do not know why it was :) I guess to many tabs were opened.

Spec: 
Google Chrome 17.0.963.79 m 

Intel Duo - Core 3.20 Ghz, 4GB RAM I
Internal Intel video card of about 1GB shared memory.

Physics with Ammo.js + Three.js by Chandler Prall