There are lot of websites that allow you to send free sms from your pc. However 160by2.com seems to be the best among the lot. I have not figured out how they manage to make money though.
They also offer an widget for we bmasters to integrate free sms service to the bog/websiite. check it out below.
Update: i have removed the widget as it was slowing down the blog.
Good Trysend free sms in india with 160by2.com365|just some value|9