http://www.investopedia.com/terms/p/pennystock.asp
A stock can be worth any amount of pennies, really

. The reason why you make make money really fast is because the amount you make depends on the percent by which the shares you own rise.
So, when you buy X shares, worth 30cents each, and they move up 30cents, you have doubled your initial investment. On the other hand, if you bought X shares worth $3 each, and they move up 30cents, you get only 10% profits.
Personally, i'll keep any from these penny stocks unless i really know what I am doing. They have a risk of becoming worthless, so yup, i'll rather keep away from them for now(beginner that i am

). You can ask Spence about them though, he knows a bunch.