ever found a guitar gimmick/mod that you actually liked/use for more than 5 mins?

TheMarlin

I’ve got a strat with a coil tapable PAF at the bridge, and passive treble boost circuit.  I do like that! 

Stuckfast

Tronical robot tuners (yes I know we're meant to hate them, I love them)

I have one of those Hipshot B/G benders fitted on a Tele... I would use it more, but the tuning stability just isn't good enough.

Fred Kelly Bumblebee thumbpicks

Musicwolf

Short trem arm on a Strat (as used by Gilmour).  Although I prefer this on my Strat it didn't work for me on my PRS

martinw

No-load tone pots on humbucker guitars.

Great for getting an extra bit of single coil-y bite on cleaner sounds, then just nudge it off 10 when using loads of gain.

Nothing to lose!

roberty

+1 for treble bleed / 50s (either is fine)

Top wrapping! I'm one of those pricks