Vonage, the leading VoIP service has come out with pretty interesting device known as v-phone. It is a tiny, bright orange colored device attached to your key chain which you can take with you any where and connect to any internet connected PC (obviously broadband) and start making calls through your own vonage account. I love this idea.
I called the customer service and only problem that you have to purchase other plan. I am using Vonage VoIP service but I can not add it on to my existing service and have to buy another plan which is not right. But otherwise this idea is pretty cool.