ok, i thought about and i thought, that even though this is dangourus, couldent we simply connect the 2 ends of the motor ( standard motor ) to 2 digital pins, and lets say we make 1 pin high, and 1 low, the motor would go one direction, becuase it is connected to ground and 5v, and when we switch the highs and lows, the motor would spin the other way!
we could put a resistor for safety, and since it's simple 5v to ground, no damage should be done, right?
It's a really bad idea, but as first-hand experience is usually the best teacher, go ahead and do it -- I'm sure the vendor that sold you your Arduino will happily sell you a new one. Okay, I'm kidding; don't do it; build an h-bridge -- there are circuits all over the Internet that you could use.
In the BEAM robotics area, they've done a fair amount of research in driving motors from non-traditional chips like standard logic. A winner seems to be the 74ac logic family, which has a fairly wide supply voltage range and fairly high current output drive. Typically, several outputs will be paralleled to get higher current. Note that most of these will insist that the motor drive voltage is pretty much the same as the control circuit (arduino, in our case) voltage; this is good for some "pager" motors and the relatively efficient motors you find inside CD drives. Many toy motors require higher current (300mA or more) and/or higher voltage, and they'll require more conventional motor drivers. There's a bunch of data here on the BEAM Motor Driver Circuits page. (Better to burn out a $0.50 74AC240 than a $5 AVR.)