Quillpad is a free online typing tool for 10 south asial languages. Yesterday I was having time free time in office so thought of searching for an API that helps writing bengali. And I landed in http://www.quillpad.in/bengali which is more than what I was looking for.
It's very easy to type in Bengali in Quillpad. For example, type 'apni kemon achen' in the Quillpad editor. Quillpad will convert it directly into Bengali script. If you write a word like 'bishesh', first sh should become 'শ' and the second sh should become 'ষ'. Quillpad will intelligently do that for you. No need to use shift keys or to memorize any key mappings. So 'রাষ্ট্রপতি' can be written by typing 'rashtrapati' or 'raashtrapathi'. Quillpad can also predict if multiple words are possible for your input. You can click on the word to select from those options. In addition Quillpad allows you to type English words freely in between Bengali words. It intelligently transliterates them into Bengali. Here is one example -
বাংলা টাইপ করা সহজ
As a quick test of using the WYSIWYG editor of Quillpad, I created to a blog in wordpress http://probasheamardingulo.wordpress.com and a blog in blogger http://probasheamardingulo.blogspot.com/. It looks so easy and convenient to me. I think I will continue writing in the blogger because it allows me to increase the font size of the content while to increase font in Wordpress I have to upgrade to premium.
Here is a New York Times article that you might find interseting and relevant.