Vocal pitch pipe? How about a harmonica--or better yet, one in each key you favor. It can give you not only the starting note but a sense of the harmony.

My problem with performing is often that I don't warm up sufficiently: my rhythm is off, my hands are stiff, etc., and coupled with another problem, i.e., that when I'm nervous I tend to start playing something a lot faster than normal, faster than I can play it, causes me to mess up, or at least to fail in satisfying myself. I have worked out a very nice clawhammer version of "Jimmy Brown the Newsboy" which I can play quite cleanly at a reasonable place, but taking an early solo at The Starry Plough I started it at least fifty percent too fast and really butchered the breaks. My vocal went okay, though, and the audience at the Plow is incredibly kind, so I survived and even got a few compliments, even on my playing.

Just remember (I keep telling myself) to take a few deep breaths before you start, find the correct tempo and pitch (I get it listening to whatever instrument I'm playing), and start.

Oh, and a bit of creep on the subject--but right on the title of this thread--a couple of years ago some friends and I were sitting in about the second row of the Freight and Salvage, listening to Laurie Lewis and Tom Rosum. As they were about to start a song, Laurie's guitar mike suddenly tilted down: it didn't drop, it just pivoted suddenly downward and she joked: "Oh, the disappointment..." and I couldn't restrain myself from asking, "Which is more disappointed, the mike or the guitar?" She looked at me strangely and said she wouldn't respond, there were children present. My friends pretended they didn't know me--hell, I pretended I didn't know myself. And this was long before I knew Catspaw, so I can't blame his influence...

--seed