I have thiis....
http://www.wbo2.com/2a0/default.htm
Gives me full wideband output, readings are given to me when plugged into my laptop (or external display), and I can hook it up to all of the sensors in my engine, or the programmable ecu ill be using. Allows me to datalog all of the sensor readings against time or rpm, over a whole day, and then go back and review exactly what the car was doing, ie a/f ratio against boost level, air temp against revs/boost etc...anything. Good for fault finding too, you can see dips and spikes in faulty sensor readings plotted across the screen..