Allow using a PDA instead of a ID in machines and vendors.

[Frank_Stein]

Some machines actually do this, where you can just whack it with a PDA with the ID in. Other things that require you to insert the ID do not.

I'm all for just having wacking things with an ID loaded PDA working all around. You can explain it as the PDA having a built in card reader that transmits the authentication code to the required machine through wireless signals. That's probably handy for hackers, somehow?