I also keep all my song lyrics (and some Midi files) on my HP Jornado PDA. Sometimes I do use it to refresh my memory, but more often so I can say to someone else - "You want the words - copy them down from here".

I usually find that if I hear a song that I really want to learn, then it's not difficult memorising it. I never memorise accompaniments - I tend to "busk" them every time. When anyone asks me for the chords to a song I have to pick up a guitar and sing the somg to get them (and I tend to play differently in each verse).