Re: "I perform this mod on every guitar I own..."
I file the nut slots on all my guitars so that when open, the action is similar to having a capo at the first fret. That's more of a setup than a mod, but it seems to be a point of setup that few people actually do... so I'm calling it a mod.
Other common mods, mod all my Strats to do B+M+N or B+N, install the TBX treble/bass control, variable split multiple humbuckers using a single dual or triple gang pot, selecting between multiple capacitors with a six way dial, and partially splitting and tapping using a trip pot in series.