For oral chatting in games, the only softwares I am using are ancient Battle.com and Buddyphone. Small, simple, work, consume so little bandwidth that you can play over a 56k modem line and chat and still have no lag.
And, most important, they are no spyware. Battle.com supports more than 2 players connecting to each other, but as far as my experience goes, this usually results in a messy conversation. Buddyphone is my favourite, as it has the better sound quality, but only allows for point-to-point-connections (ideal for talking to an ally in 2v2).
They are freeware, so I can mail them to anyone who is interested.
Darkness is a state of mind
Valor is the contempt of Death and Pain. (Tacitus)
Problems worthy of attack prove their worth by hitting back. (Piet Hein)