People always say networking is key -- it helps you maintain alliances at work, helps you network with important people (inside and outside of your current work) and it also generates positive interactions when you consider your co-workers as people who you can help, and who can help you.
I've had a few junior employees tell me they don't know how to network with people. "Jess - you make it look so easy! You always get people to stop and chat with you in the hallways. And then you're the only one that can get them to buckle down on those important deadlines we have to meet!"
I learned about making "5 second friends" when I was working (very briefly) at Starbucks. Hello, how are you? Met with general interest once you get to know someone more. Ask them something specific - how was your weekend, did you go rock climbing? How are the kids doing in school? Start with things that aren't work-related so you can build rapport with them, then focus on the work-related business when needed.