With people I don't know well who are my Facebook friends, I see Facebook as a way for us to get to know each other better - reading posts, viewing pics, liking, commenting, etc.
With people I do know well, but with whom there is a barrier to spending time together (either life or geography getting in the way), I see it as a way to maintain the friendship and let it continue to flourish, in the same way as I described above (reading, viewing, liking, commenting).
In both cases, Facebook is a way of spending time with people, but with the ultimate motivation (where possible) of being together face to face. Not because we feel obligated, but because we are actually drawn to each other, both by what we experience through our online interactions and by our history of being with each other (even if it's been short, brief, etc.). We want to get together and we make plans to that effect, even if it's months (or sometimes more) between visits.
These interactions take place throughout the day or week in short, but relatively consistent bursts.
And now...drum roll, please...the spiritual analogy:
When we intersperse our day with Scripture, prayers, praises, thanksgiving, worship music, and keep a constant (albeit constantly interrupted) awareness of God, it helps us maintain and grow our relationship with Him. It also makes us desire Him more. It motivates us to set aside time alone with Him, which should be what we most look forward to. We may not make it happen every day (Lord knows I don't, though I wish I did), but by "practicing the presence of God" (see book by the same name), we are nourishing our spirits and the longing we have to be intimate with our Creator, Savior, and Lord.