http://www.highgrow.us/
It's a freeware program that lets you grow virtual weed in real time. You choose all the setttings for light and fertilizer, and lovingly nurture your plants to life. There's like a million different seeds to choose from. This program totally kicks ass, I just planted some White Rhino a few minutes ago. Has anybody ever played that stupid game Cats? It's basically a heterosexual version of Cats.
