I built something similar a while back that includes reports about what the browser is capable of. http://aboutbrowser.com/

You can also share links w/ your report, which is good for troubleshooting. http://aboutbrowser.com/view/JORMR

I found myself looking up device pixel ratios and screen resolutions over and over the other day. I threw some code together to make it easier on myself and then thought that maybe other people might find it useful as well. If you have a suggestions for improving or adding news things please do let me know.