I've always just kept the needle package out next to my machine. I always know which needle is in the machine by finding that pack. The rest of my needle packs are in a tray further away. This doesn't help with remembering to change it after 8 hrs. of sewing tho, and throw that one away.
I got a handy needle guide published by Schmetz at my local sewing machine repair shop. They were handed out when I had a lesson for my machine. It covers all the different needles Schmetz makes, what it's feature is and the fabric used with each type. There's also some needle anatomy inside too. On the bottom of each page there's a listing of many different fabrics and the type and size of needle you should use.