Nerf guns. 'Nuff said. Seriously! :-)
Occasionally, say once a month, bring in lunch into a common area and let everyone put their feet up for an hour and just relax. Don't waste money on oh-so-fancy food, but let everyone toss in their ideas for what to get, then vote on it. Do that a few times and you'll find out what are everyone's favorites. Don't use the time to harangue the employees or do pep talks. Use it for brainstorming, talking about ideas for new products, or even a gripe session. Give them a chance to talk and be listened to.
Oooo, here's a thought, combine code-reviews and Nerf guns over food at lunch. Someone writes some code that sucks they get nerfed by the rest of the team. :-)
Bring in a refrigerator, and stock it with some decent sodas and bottled water. Yeah, it'll cost the company a couple bucks, but the people tend to chill out a bit when they can get up, saunter over to the 'fridge, grab a cold rootbeer or whatever, then wander back. Don't nickel and dime the employees with $.75 sodas.
Put in one of the modern coffee machines that lets people choose what type of coffee or tea they want. I gave up on coffee but love my morning green tea. We have these spread around our office area, and I don't think there's been a day go by that I didn't sear my mouth on my morning tea. :-)
And, if the standard is two monitors, do not hesitate if someone needs three; Be willing to go one more, or two with reasonable justification. I currently have two, and am waiting on an additional video card to add two more, because I'm sick of having to juggle multiple SSH shells, editors, browser windows with docs and PDF versions of my manuals, plus the company mail and chat systems. We've got systems with five and six monitors for our networking management folks, so four for a senior developer isn't extravagant.
I'd also recommend that quiet be the office policy. Some people want music and think it's their god given right to play it loud enough to be heard several cubes away. Wrongo. Music needs to be played through headphones and should not be audible outside their cube.