Google has a neat transliteration tool, which allows Hindi (or other Indian scripts) to be typed using the English alphabet. For instance “mera” is transliterated to “मेरा” (Hindi font support needed)
I’ve used that to write gIndic, a Firefox extension which provides transliteration service on any website. Like the Google service it supports Hindi, Tamil, Telugu, Kannada and Malayalam. It works on both Firefox 2 and 3.
You should now see the gIndic icon - the letter “A”. To start transliterating, click on the “A” icon and choose your language. Click on “A” icon and choose the “Default” option when you want to type in English again.
Type a word and hit a space to translate it. It works on input and textarea tags.