hey guys, i was wondering how far your bridge humbucker is from your strings in mm's ? thanks
mines about 4-5 mm's on my Epi Lp Standard

Epiphone Les Paul Standard Plus-Top, SH-2 and SH-5
Ibanez GRX20
Baron Acoustic
Peavey Valveking 112
Roland Cube 15
Dunlop Crybaby From Hell
Dunlop GCB-95 Crybaby
Boss MT-2 Metal Zone
Boss PH-3 Phase Shifter
Boss BF-3 Flanger
~2 mm below the thin strings and ~4 under the thick B
Brigadier of the 7-string legion. 7>6

Fender Telecaster
Schecter Damien 7
Engl Fireball
Mine's flat with the surface of the guitar. I have really hot EMG pickups, and that's right where I strum, so keeping them low keeps me from hitting them and cleans up the output a little. It's still more than hot enough.
I crank both my pickups as high as they can go, so that when the high and low E strings are fretted on the hgihest frets, they both just touch the top of the pickups. Then I lower the side of the pickups closest to the high E by about 1.5mm, and I lower the bass side (nearest the low E) on the bridge pickup by about 2mm, and on the neck pickup by about 2.5mm.

In other words, almost as close as they can physically go.
It depends on the guitar. In most cases passive pickups won't be too close (magnets will grab string vibrations and screw up intonation). My guitars with EMG's I put as close as possible though.
I don't know, exactly, but very close on my SG. One of the first things I did to it was raise the bridge pickup. Very loud.
6mm on my guitars
LTD MH-1000
Ibanez RG350EX
ibanez GSA60
Line 6 Spider III 30W
Peavey ValveKing 112
Boss GE-7 EQ
Electro-Harmonix Small Clone Chorus
Digitech RP350