You don't tell us how you're proposing to use biometrics and what current systems must be supported.
However, there are good systems available from (for example) SAFlink to enable biometric authentication (fingerprint, face, voice or iris) to be added to AD, eDirectory or eTrust environments.
As others have commented, there are good systems for physical access (there are numerous Asian companies manufacturing fingerprint door locks) and for time-clock systems based on hand geometry (Recognition Systems P/L) and fingerprint (many players, Identix is probably the best known).
If you want more info, just ask.
David.