I created WiFi bathroom scale that posts weights to the web. You can see my live feed here:
http://h1.ripway.com/asmithmd1/2768.txt

and a Graph here
http://h1.ripway.com/asmithmd1/WeightData.html

I bought one of these scales because it has a serial port that spits out the weight every time someone steps on it

I wired up a serial port input to a RCM4400W

With about 4 hours of C coding I have the board connecting to the strongest open WiFi access point and listening for weights from the scale. When it gets a weight it posts the data to my server.

Of course the scale and the processor are overkill for a production version but are a quick way to prototype. In small quatities the scale is $175 and the processor/WiFi chip is $99.