One of my favorite hacks is No Meeting Wednesdays, which we borrowed from Facebook. With very few exceptions, everyone's calendar is completely clear at least one day out of the week. Whether you are Maker or a Manager (
http://www.paulgraham.com/makers...), this is an invaluable tool for ensuring you have some contiguous space to do project work. For me personally, it is often the one day each week I get to code.
This is explained a little further in
How does Asana approach No Meeting Wednesday?