Generating QR Codes with Google

The google chart API has this feature.
http://chart.apis.google.com/chart?cht=qr&chl="+[YOUR_TEXT]+"&chs=[XSIZE]x[YSIZE]"

For instance
http://chart.apis.google.com/chart?cht=qr&chl="Hello World"&chs=120x120"

will generate this