For my own gigs I don't use music, but I'm sitting in with some groups in the next few weeks, and I've finally made the move from Real Books to an I Pad. I'm using a program called Gig Book and it seems great. I can make a set list of just the tunes we'll be playing. Also, there will be a singer at some of the gigs and I can transpose the chords to the singers key in I Real Pro, export that to Gig Book, and there is the transposed chord chart in my set list.

Others use IPads or still using the cherished old books.