By popular demand I have added the Android versions of Firefox and Chrome to the site.
Note that the browsers are currently hidden by default (together with Opera Mobile), and can be displayed by either enabling them in the Options panel, clicking the "Show all versions" link on a given table or directly from this link:http://caniuse.com/#agents=All
The reason for this is that at this point these browsers all have very little market share, and should be of low priority to the average developer that already has many other browsers to test for. But as these are high quality browsers with a lot of feature support, I felt it to be important that the information is available.
In the near future this selection will be stored in localStorage so each time you visit the site the last selected browsers will reappear.
One final note is that since apps tend to be updated regularly and testing older versions of Android apps is near impossible, only the latest version will appear on the site for these browsers.