Question: I consider Facebook to have information that is personal and that I only share with close friends and family. However, in my new workplace I’ve been asked several times for my Facebook username and/or have been *friend requested* and I don’t want to sound rude by telling them that I don't want to add them as friends. 

Any suggestions on the way I should handle this?

Answer: 
My policy, when I was on Facebook, was very simple: Friends were just that, *friends*. I didn't add acquaintances, I didn't add every coworker, I didn't add folks whom I knew by sight but hadn't spent a significant amount of social time with. Period.

You don't have to respond to the request. Just ignore it, and let them deal with it. But you also don't have to feel bad about saying "Thanks, but no; I'm keeping work and personal life separate."

Ditto for any other social medium, unless you're in a situation where you're trying to do business via same... and then I'd suggest a separate account.
My approach is to have largely disjunct sets of social networks. You're a work colleague? Fine, I'll add you on LinkedIn and Google+. You're someone I met socially and you want to link up on Friendster? Fine.

It does go both ways, I know a lot of people who socialise in a work-like way. They have a small business, they're Amway victims or whatever. If I don't see them as related to **my** work I will keep them on the social side. Or the black-list, if that's how I feel about them.

I have cross-over stuff, like selling photos and hanging out with photographers, so I run multiple streams/sites for my photography. I generally add those people on both career and social sites, but I also partition them within the site. I have facebook groups for "family", "friends" and "clients", for example.

So my answer to those requests would be "why don't we use LinkedIn" (or whatever).