Grand Central is one that looks pretty interesting. It reminds me of the product I saw years ago called Wildfire. I believe Wildfire was only available for California phone numbers at the time that I saw it. I believe there was a charge for it as well.
We'll have to see what direction Grand Central goes now that it is a Google product and if it remains free.
I have put in my request to reserve a number as I would like to try it out when it is available. I doubt anyone I know is going to get an invitation to the beta, but I still might try to track one down.