Compatible with both cellphones and PCs, the Aura Mobile Bluetooth speakerphone has four hours of talk time, 24 hours standby, echo cancellation, dual speakers, and weighs only nine ounces. There are also various accessories for it, like car power adapters and wall adapters, as well as an external mic. Available now for $149.99.
We'd get one for our cars if our phones didn't already have speakerphone already. And if it were a bit less than $149.