1) Respect. By that I mean professional respect - I want to feel that my contributions are valued and that people recognize my talents :)
2) Team. Working with dirtbags is miserable no matter how much you get paid. Sure, I'd do it if you threw enough money at me, but all else being equal, I'd like to work on a team full of smart, pleasant people.
3) Growth. Learning opportunities (conferences, training, etc.), promotions, stimulating projects, etc.
4) Time. As in my time. Overtime is kept to a minimum and really only happens when there is a true emergency. This kind of ties in with #1.
To an extent you can substitute cash for any or all of these. However, if your working environment and/or culture is toxic, you're going to have trouble with retention no matter what else you do.