What headset/radio products exist for bike-to-bike communication?
Years ago, when my wife and I started riding together, we got a pair of cheap two-way-radios, with headsets that included VOX.  This allowed us to talk even when we weren't riding side-by-side.  And since we weren't trying to talk from a mile away, it didn't matter how cheap the radios were.

Of course, this requires you coordinate with your co-worker, both have radios set up and tuned to the same frequency.