While surfing net, I came across this interesting online business solution called Billing Boss. It is a free online invoicing tool, targeted for small businesses and freelancers. One can create, email and track the status of invoices. After watching the small video demo hosted on its site, it looked very easy to use this tool.
Since I neither run a small business nor I am a freelancer, I can't use it. But I guess it will be interesting to see how this site gets used in future.