Buy or DIY your cat's dream home. Meow!
The Shark
Buy!
Source: thinkgeek.com
The Rocket
DIY!
Source: blog.makezine.com
The Milk Carton
By these designers, but not yet on the market.
Source: design-milk.com
The Surreptitious Tank
Discontinued, but worth a DIY!
Source: curiobot.net