I've been looking to audition for a good working band a lot lately. If your doing this, or have done it ,I'm sure you have run into walls while trying to tackle a large set list. Usually with all working bands they are in need of someone to fill the spot quickly and efficiently, so during the audition in which you've had a limited amount of time to learn the set list you naturally want to get down as many songs as possible. Knowing the key of those songs is key to getting through it, but I think there are other things that can help.
1. Let's say it's country and all of the songs have easy progressions but a lot of them seem the same at a listen -same chords, same tempo, etc. I always try to memorize some of the vocal hooks and melodies in order to make a solid connection to the song. It helps with the changes that make the song differ from the others in it's genre.
2. Watch the video. You may not be familiar with the artist so it's good to place a face with a name. This way when they call a song name and artist off the list you will think to yourself, "Thats the guy that looks like (insert description) and plays the really nice Strat." Thus in turn making another relation to the song itself.
3. Youtube or Myspace. You probably wont have all of the music in the set at your fingertips unless you have an enormous cd collection. If your lucky the band will burn the songs on a disk for you. But you're doing this on the fly right? So probably not. Turn to a internet source that will have the music available, move your gear close to the pc and get to work!
4. Tabs or chord charts of the song with lyrics. It's the easy way, yes, but you want the gig right? Once again you have limited time and seeing the song title, artist name, and lyrics on paper will allow your mind to make a connection to the song as well as letting you know what changes are where.
5. Listen as much as possible. Even without a bass in your hand you have to listen to this music as if it's your favorite style. Even if it's not. If it is'nt ,you should still find something you can appreciate in the song that helps you find another connection to it.
These are just a few things I do when trying to learn stuff on the fly. Hopefully it will help someone and maybe you have some ideas of your own that will help someone as well.