I work in a restaurant with a bar. When there, I wear an apron.
The apron I keep some cardboard coasters, a couple of books of matches, ink
pens, some breath strips, a wine key (pocket knife with a cork screw and
bottle opener).
Actually, the wine key normally winds up in my pocket through the day.
Because I also work some free lance bar jobs, I have a 'bar bag', which is
actually a lunch bag with a zipper closing. That I keep stocked. It includes:
latex gloves, a cutting board, a paring knife, a wine key, a dozen speed pours
in a zip lock bag, a half dozen speed pours in a plastic tub, a zip lock bag
with aluminum foil and more zip lock bags, a shot glass, an olive spoon (from
Tupperware, it has a scoop for picking up olives, and some prongs on the top
to skewer them), a small bottle of hand sanitizer, some wet ones, dish washing
liquid.
I also keep in my car this plastic bag with two dozen speed pours and a wine
key.
I am sure that there are some other 'necessary' things that I need for my bar
bag, but as soon as I run across these things, I'll get them.
I keep my Palm Pilot with me at all times, and I have my drink recipes on the
palm pilot.