Thinking of building a DIY web-powered robot that you can control through your browser or smartphone? You might want to check out ioBridge ethernet control modules and this DIY web-powered robot made using them.
The robot uses a pair of serial bluetooth adapters to form a wireless link with the ioBridge IO-204. The serial levels of the IO-204 are TTL and a circuit using the MAX-232 was required to allow the serial interface work properly. On the robot is a set of serial servo drivers that control the steering and speed.