What is a good simulating business site?

[Lilli is Silli]

So I want to play one of the fake simulated businesses, you know like pretend to manage and own your own business online? I always thought they were really fun, but I can't remember the ones I used to go to so I need some good suggestions. Simulating the businesses, remember. I don't want anything to do with a real business where you actually get paid and stuff.
Oh I forgot it has to be a website because I left all my tycoon games at home