How do you use twitter / facebook to promote your sites?

[onlytease]

OK, lets try to get some useful business discussion going

How do you all use social media to promote your sites?

I will be honest in saying we use them a little, but get nothing from them - so what is the trick to it? I keep people saying that Twitter is brilliant and they make a million sales a day from it, but I just don't get it.

Anyone want to enlighten me?

Cheers Paul.