COW is a browser-based milti-player virtual world which encourages
creativity and fun.. No plugins or clients required.

All users can create objects from the start.  
There is a training shed with a tiny robot who will guide new users
through the basics.

Objects have 'worth' and can be bought and sold.
We have a bank and several shops. 
There is also a post office and a postman who delivers when you login.

If you prove yourself worthy you can learn COWScript and code objects.

All of the commands are simply objects coded a specific way so 
making a new command is as simple as creating a new object 
and coding it.

Building new locations and creating new objects is done like this:

build a rusty gate to an old warehouse
go to the gate
create a rusty old car
paint it as tomato
create a dusty coversheet
paint it as lightgrey
put it on the car

Naturally you can say, do, shout, think, sing and ponder to
communicate with others in the same 'room' as you.

Some technical info:
COW is running from my own dedicated server so is very fast 
(Its running from a 32Mb RAM drive).  
Its a single perl script with a few supporting CSS and image files.
COWScript is a scripting language I have designed specifically for 
coding objects in cow.