That's an interesting site, not seen that one before.

One backdoor code that I've heard of before but it always make me chuckle whenever I read of it is Boat anchor mode.....

C-E-C Skip-to-end - Turns on "Boat-Anchor" mode. This convinces the TiVo that it should behave as if it has no guide data. Boat Anchor mode is automatic when the unit runs out of guide data, so this is probably only for testing purposes. A bit useless, really.