For about the past week I’ve been making a lot of use of the Polycom C100 in conjunction with a copy of Eyebeam provided by ZipDX. The C100 is a great little USB speakerphone device. It was one of the first devices from Polycom the supported wideband audio, providing that you have a similarly capable soft phone client.
I must admit that mine is the C100S model which is designed to work with the Skype client, although there are models that are not client specific. As a practical matter the only functions that are client specific involve the use of the five buttons on the device. The buttons support volume up, volume down, place a call, bring the soft phone client to the foreground and mic mute.