Seat Belt Chime - Fixed!!!
Here's how to disable the chime WITHOUT disabling the airbag sensors. Like imcastock said, if you disconnect the plug, you WILL get the "Airbag" light since that wiring harness also feeds to another sensor right next to the seatbelt buckle.
Disclaimer: I am in no way taking any responsibility for any consequential results from this DIY. If you get seriously injured, maimed, dismembered or die because you forgot to put on your seatbelt, you assume full responsibility!
OK, here goes:
1) Look at the seatbelt buckle next to the center console glove compartment and you'll notice two little Torx screws. They're the "tamper-proof" kind, so you'll need find the exact size for this DIY. They usually sell 'em in a set so that'll be your best bet.
2) Remove the Torx screws and pull back that cover. Inside of that cover, you'll see a little circuit board with a black sliding contact. Simply remove that contact from the board and TA-DA, you've silenced the annoying chime.
Explanation: The circuit (blue and yellow wires) is normally closed when the black sliding contact is in the outermost (seatbelt released) position. Once you've buckled the belt, it opens the contact. This is what you've done on a permanent basis.
I hope this helps everyone who's been driven crazy by the seatbelt chime that refuses to turn off. Good luck!