I have been using Microsoft Hohm since it was released and I love it. I love it because there is no other tool like it and I love it because of how well it shows information about the energy usage of your home.
For example, here is a graph of the energy usage of my home:
It not only shows me the cost per day, but also information about the temperature. There are options to view the graph by only electricity usage and by natural gas usage. Its nice, because, it lets me track my usage just as I would track my money on my bank’s site.
Hohm also shows you a breakdown by usage (which perplexes me, as I am not sure how they are deriving these numbers. my best guess its based on my home’s profile, where I put in information such as number of bulbs, water heater, etc.)
As of now, I think the only provider that is supported is Xcel Energy (Don’t know why more energy providers don’t provide this service).
If you want real-time usage data, then, check out Blue-Line, which uses a meter monitoring device in conjunction with Hohm to provide real-time monitoring: http://www.bluelineinnovations.com/