Google Indic Transliteration
From Seo Wiki - Search Engine Optimization and Programming Languages
This tool first appeared in Blogger, Google's popular blogging service. Later on it came into existence as a separate online tool. Keeping in view its popularity it was embedded in GMail and Orkut. In December 2009 Google released its offline version named Google IME. The name of this tool is a bit misleading. Instead of Indic Transliteration it should have been named something like Indic Typing Tool.
This tool from Google is based on dictionary based phonetic transliteration approach. In contrast to older Indic typing tools (which type by transliterating under a particular scheme), it transliterates by matching the Latin words with an inbuilt dictionary. So, users don't need to remember the transliteration scheme due to which this service is very easy and suitable for first time typists or beginners which are used to Romanagari.
For transliteration between Indic scripts, there is a separate service named Google Script Converter.