I found this article on how to modify a common Linksys WRT54GL router to add dual serial ports and an SD memory card to it (for GB of storage). This router runs a version of linux and is very hackable, so its great for wifi control of robots. The serial is 3.3V so it looks like an RS232 chip is unnecessary to use with a microcontroller UART (level shifted for voltages other than 3.3v). Maybe you have one laying around, what are you waiting for?