As an employee who has worked in environments that have those little perks, like soft drinks, entertainment activities, and other such things, I can say that the number one perk that can be added to make employees more productive and happy is flex hours. Allow your employees to choose their own starting time, with core hours that they must be at work, and it instantly becomes a much better place to work. When the employee feels like they have some control over small things like that, it makes them much happier and more productive. The free soft drinks are nice, but that only seems to work at small companies.