From the perspective of a developer what do you consider to be the most important environmental factors or work place perks/policies that contribute to increase productivity?

For example, my top four includes the following:

No internet restrictions - Because honestly ever few hours I need a 15 min deload, which usually involves checking my gmail account and or browsing a few choice site.

Personal office with a door - for obvious reasons

Dual monitors - do people really develop software with one monitor still?

Flexible hours - This could be interpreted in different ways, but basically I really appreciate that fact that I can roll into work at 7am, 11am or whenever and the time police aren't on my back. It is just understood that I will put in my 8 hours or more if needed and get my job done however that works out.