Why put your business out on Facebook?

I've notice the last few days that I have some friends that are getting pretty mouthy on Facebook. Don't get me wrong, I love facebook. I love being able to connect with my family and my friends that live far away. I can share pictures, video's, and updates of what my family is up to.
What I do not share on facebook is fighting with my friends, family, and anyone else. I do not post about things that are overly personal. Yes, I might post that I am having a bad day, and that I have dealt with some nasty customers at work, my kids are getting on my last nerve or that I need to go on a vacation, that I wish the xbox would magical disapere out of my house. I think you all get my point.
And yes, I have been gulity of posting somethings that I porbaly should not have ever put out there, but it just seems to me like people don't care much these days to put thier "business" out thier for everyone to see.
Anyone else have friends and family that do this? Does it annoy you too?