I Like You...Don't Run Away

How do you talk to a guy you don't know without seeming creepy or desperate? It's a question we've all posed at least once in our lives (let's be honest here). In this case I'm going to cover co-workers or people you know through business, but I know this conversation could last for much longer (and probably will re-surface).
So you've been scoping out the cute guy who sits two floors down. You have no reason to talk to him - no shared projects, no department-to-department interaction, and no mutual friends. But he's oh-so cute! Well, here are my suggestions:
Organize a group outing with other co-workers and invite him to join - coffee break, patio after work or lunch
Ensure you attend all office events and participate in any extra-curricular activities - BBQ's, sports leagues, Holiday parties; it's much easier to strike up a convo when you're not hovering over his cubicle
Find a reason to learn more about what he does in his job role - perhaps you're on a new project where that knowledge could be really helpful...
Use him as a sounding board for new work-related ideas - you are implementing a new system or program in your department and you need to know how it will impact others in the organization (aka him)
Blatantly ask him what he's doing after work this Friday and if he'd like to grab a drink, or if you're not that brave, if he wants to walk to the nearby cafe for lunch
Organize a sports pool or captain a team for a charity run, and encourage your co-workers to get their departments involved. Never underestimate the power of six degrees of separation!
Find extra reasons to be on his floor - personally visit a friend instead of emailing or visit the mailroom once a day
The key to avoiding creepiness is to involve others when possible in the beginning, and don't push it. If you feel that he's reciprocating - taking you up on your offers, giving you the once-over when you walk by, or asking you to join him in return, you're good to go. Conversely if you invite him out and he doesn't seem to bite, just drop it and you will still be able to pass by with a "what's up" and maintain your professionalism and stellar reputation.