Google's OneBox, the search/URL/etc box in Chrome and search bars has been updated. You have been able to enter a conversion, say 5kg into pounds, in the box and get an answer, but now it's interactive where you can easily change the number and units in the results box itself.

I entered "5kg = ? pounds"

You can click on the "Mass" to bring up a drop down menu of different measurements, including temperature, velocity, volume, and more and clicking on "kg" or "pound" brings up a drop down menu to change the units.

This is a great resource for students and teachers needing a quick and easy conversion calculator anywhere.