Best pedal for singer-songwriter?

As Anders would say, "Campfire chords"

I do little live gigs, I'm wondering if there's a good pedal anyone would recommend.

Hi what a wonderful day to play guitar 

What kind of guitar do you use for these gigs?  What kind of music do you play at them?  Is there some specific type of sound (timbre) you are trying to achieve that you can't with the gear you currently have?

The answers to those questions will really help determine what kind of pedal would be beneficial.

Hope that helps!