If you could only use one pedal...

GuitarMonkey

This may have been done before, but if you could only use one pedal what would it be (multi-fx excluded of course).

I don't use pedals much but if I could only use one it would be my Charlie Stringer Snarling Dogs Wah for the expression it adds. 

ICBM

Dirt pedal: Boss DF-2

"Effect" pedal: Roger Mayer Voodoo Vibe

JDE

Probably a delay of some kind - Boss DM-3, Eay Huge Aqua Puss. Nothing outrageous.

monquixote

Assuming I had dirt on the amp then probably a trem. I suppose I can't have a Flint because it has more than one effect so probably something like a Tremulator.

If we're talking clean amp it would have to be a Liquid Sunshine. It hasn't got enough welly for heavy, but it is amazingly good at acting as a light drive in to a clean amp, pushing a dirty amp, acting as a clean boost, acting as a treble or bass booster etc. 

EdGrip

Musket/Muff-type-thing, or Catalinbread Belle Epoch?

Probably the Belle Epoch. I could turn its little preamp right up, amp overdrive, and tape delay goodness. BOOM.

ROOG

Flint, trem-n-verb, or does that count as two?

IanSavage

Assuming that we're allowing a tuner as 'granted', Boss ODB3. I AM a bass player primarily though on guitar, I'd cheat and use a Peavey Delta Blues amp which has footswitchable dirt and tremolo, so I probably wouldn't need anything on the floor - maybe a chorus, Small Clone or something. 

timmysoft

The ones that spring to mind for me would be: for heavy modern rock - mi audio crunch box v3. For radio rock - rat2. I don't really get involved in too many other styles!

Branshen

My Keeley BD-2. (expecting viz to give me another wisdom for this)

viz

I can't play without this, so I guess this. http://www.robertkeeley.com/manuals/ts9dx_flexi_4x2.pdf

littlegreenman

Amp dirt assumed, Weeping Demon Wah. I use wah as a filter almost constantly, very rarely as an actual wah. I blame FZ

Dave_Mc

I know you disallowed multifx (with good reason), but what about those pedals that have a couple of effects in them? You know, like an od and boost in one, say. Could I say one of those? I've never actually tried them much, so I dunno which I'd prefer, but I tend to use two ODs so for the sake of the thread that'd be my choice... )

EDIT: That's assuming I get my free choice of amp, too.

not_the_dj

Wah

Bellycaster

I'd use a Wah in front of a Hughes & Kettner Switchblade.

Bidley

As long as the amp does dirt, a Boss BF2. Gives a slight volume boost with the flangey goodness.

richardhomer

Boss CE-2. In fact there was a time when one of these WAS my only pedal!

MattG

Valve sporker, it even makes my playing sound good!

Forge

Easy one for me - Fuzz Face based pedal.

Stick it full on in front of your single channel amp and drive it with your guitar volume to access clean, light OD, drive and fuzz.

p90fool

6-band graphic EQ.

Heartfeltdawn

Diamond compressor. All I need for my clean jangle. 

equalsql

My own built 'Overbite' pedal as seen in the picture below. It's basically a BB plus clone, but I had to used multi-combinations of capacitors  and resistors to try and get the exact values required and for some reason it has made this pedal particularly sweet with single-coil pick-ups. It is killer on the neck pick of my 52 Tele. I have yet to find another overdrive that can touch it.