Ok, I know a lot of you guys do this stuff all the time, but I'm a noob and this was a novelty for me so I feel like I should relate my experience.
First a little background about myself. I am primarily a violinist. I'm studying violin performance in college. I started playing bass guitar about 5 years ago, mostly self taught (if such a thing exists) in my begginings. Ever since coming to college I've been playing bass in jazz ensembles, learning the style and the vocabulary. I've only been at it for 3 years, and even then on the side exclusively, without putting nearly as much time into it as I do for my violin stuff, if only because I don't have the time. I love it, though, and learning and playing this stuff is fun. I've been in a jazz combo for a little over a year and we've gigged but all our gigs we play songs that we have worked on in rehearsals.
So, I got this gig because I know the drummer that plays in it. They had some other bass player but the guy bailed out so he called me. I know him and the conga player but I had never met the band leader (A-MAZING vibraphonist). I get to the venue and I am handed a folder with probably about 30 or 40 different charts, most I've never seen before. This is a combo gig so it's not like I'm having to read through written out lines and tutti licks, it's mostly just changes with a couple of songs having written out basslines because the intro is a bassline or something like that.
I didn't play perfect; I made plenty of mistakes. Honestly, I was very nervous and very much intimidated because these cats just blaze through changes at very fast tempi. At one point my bass (peavey cirrus) quit making sound, so I quickly went in the back room and changed the batteries out. When I plugged back in everything was fine but I later discovered the cable was the problem, not the bass. Anyway, there was also a trumpeter who was also an incredible player, very nice guy. He complimented my playing a lot, saying I was doing great for sightreading, he was very encouraging.
I must say that the highlights of this gig for me were two songs that we did where they called up a lady who was sitting in the audience, apparently she is friends with a few of the guys in the group. She's a singer, the first song we did with her was "One Note Samba" and the second, close to the end of the night, was "The Girl from Ipanema." This lady had a beautiful, yet strong, soulful voice and she sung with such energy that I just fell in love with her singing. These were songs that I knew and so I wasn't afraid of making mistakes, and overall the vibe just became so much cooler whenever the lady sung. I realize that I probably felt this way because I am not nearly as skilled as the other cats in the group and so in the instrumental tunes I always felt like my job was to keep up with them and not mess up.
The pay for this gig sucked (we didn't have too many people show up), but it was an awesome experience that I will probably remember for many years to come. Those cats really inspired me to strive to become a more fluent jazz player. At the same time, it was kind of eye opening because these are cats that can REALLY play and yet none of them do music full time. Another thing I must point out is that these jazz guys sounded (in conversation) very educated and well-traveled. I hope I can play with them again and hopefull next time my confidence won't be so low.
Anyway, sorry for the uberpost

Feel free to share your opinions or similar experiences.