[qiemem]

What about fingerprints? You don't need to buy anything, phones and such are already coming out with fingerprint readers and the technology is improving all the time. Finally, you can't lose your finger print (except in the case of extreme accidents, which exist for any type of security).

[M2Ys4U]

Fingerprints are usernames, not passwords.

You can't lose your fingerprint, but you can't replace it either - so what happens when somebody clones it?