Like the Maxim MAX4211 TI produces a (low side) current and voltage monitor with an SPI output, the LMP92064. Your processor will have to do the multiplication to get to power, but that's what processors are good for!
I believe TI has one or two others, but it will have to wait untll I get back to work on Monday.
I must apologize for not mentioning the Rogowski coil for AC current measurement. I have never had the opportunity to use one, so there is not much that I can add.
For completeness, I guess I should mention the rotating disc that used to be on all power meters. For the life of me I can't remember that name of the effect that produces the rotation and I don't know of any modern application that uses this approach.