Remote jack?

[jimbob]

I own a few boss pedals with an xtra jack next to the input jack..Although this is something i should already know, im not to proud or embarressed to ask. What is this for?  This is the right place to ask.

Most importantly, is this something id want to add to other pedals?

[Ansil]

some are for expression pedals, like on the pitch shifter from boss you can whammy like the digitech whammy pedal.  some are dual inputs for seperate processing.  some are like the old harmony pedal, for a boosted clean tone so the harmonizer could track better than say with distortion.
some are for envelope control

and yes if you like controling certain features  via an external controller it is wise to install.  

i have a distortion that i modded to have a control out, for dist and clean using a dual pot, i control the disortion with a forward rock of the pedal which also controls the volume output, ie more gain less overall volume, less gain more overall volume.

my delay pedals all have an expression out for the delay.  and when i first modded my original boss ce2b(my five dollar pawnshop prize with the broken case.). i modded the rate controll to be more like a rotovibe type sound.

you can also add functions that normally didn't exist such as delay feedback loop  another fun thing.

voltage control  etc