nice chairs is a good one, but here are some others:
1. some people don't like keyboard trays, but I've had shoulder problems after several years of working without the keyboard at the right height. get them
2. get plastic adjustable stands for monitor and keyboards immediately, not on user request. make it ergonomic, but you don't have to spend the big bucks
3. some developers need special environments (i.e. less noise, less visual distraction), but some feed off of interaction. learn what these needs are and either make it happen or don't hire them, but don't find out too late. do not handle this with white noise. it may mean they can't co-locate to be as productive, and if that is a problem, you need to figure that out
4. people sometimes need privacy. don't foster an environment that encourages people to take calls inside or meet in cubes, distracting others