I like to keep an eye on trending browsers/OSs/languages etc... I find google trends is a very useful resource sometimes but other times I can not get the information I
Such "metrics" have questionable value (but are fun to discuss). You could add a word like "program" to each language: http://www.google.com/trends?q=flash+program%2C+java+program%2C+javascript+program&ctab=0&geo=all&date=all&sort=1