Trustable Passwords	Behavioral Biometrics (voice)	Physical Biometrics (fingerprint)	Tokens Smart  Cards	Hardened Passwords	Weak Passwords
Familiar
Easy to Remember
Does Not Change
Software No Hardware
Cannot be Shared
Strengthens Over Time
Ubiquitous Access
Authentication Foundation
Non-Intrusive
Revocable

No question - a software-based, behavioral biometric, which simply adds-on to existing passwords is a good idea.  It saves money.  It saves hassle.  It implements quickly. 

Trustable Passwords is a value-add, adding benefits and working well with others too.