Not only IMVU allows people to chat with each other, it allows them to customise their own 3d avatar from head to toe and also rooms and furniture by buying items (created by fellow members) from the shops using credits.
In IMVU, when a person sign up an account. They are just guest and their nick will show ' Guest_(your imvu nick). A person can get buy credits and become an IMVU member so to get rid of the 'Guest_' and also allow them to more things in there like create items and sell and create VIP rooms and also unlock some adult features.
Since 30 June 09, there is a new version of IMVU, both members and members now are able to buy items using the client without the need to redirect to a web page, chat with more than 1 person without the need to open more IMVU windows. and more.
This are the pictures of the new IMVU client.
IMVU shop
For more information about IMVU, you can visit IMVU homepage here.