One big problem with Facebook is that you have to pay them to reach all of the "fans" of your page. Posting on one's band page won't be reaching all of them.
Even in the days of MySpace, I remember a local band posting about a gig, and that post got 6,000 "likes." Went to their gig, and I was one of three people who actually showed up.
I think that pressing the flesh and adding value to your shows works the best.
I had joined this band, that was actually on its way to becoming a three-piece. I was his first drummer, and he [guitarist/singer/owner] had just moved into town from another state. He said his first gig was already booked at The Viper Room, and he had 30 days to get it together.
This was the guy whose band I quit, but then he encouraged me to NOT quit so that he could fire me a few hours later.
I went to The Viper Room the evening of his gig, just to see how badly he failed. It was raining, and there was a line going around the block. As it turns out, he triple-booked the venue. I couldn't even get in.
Saw him walk up to security to tell them he was taking his guitar to his booth. They told him no instruments were allowed at the booth, but he did it anyway. One guard said he was gonna give him some crap about it, and the other said that "he probably triple-booked, so let him do whatever he wants."
He didn't use Facebook or any online social networking to do this.
What he did probably involved having a trust fund of some kind.
He'd wake up at the crack of 5:00pm and get dressed up as if he were playing a show. The guy was part vampire, part Prince. Always, always, always dressed impeccably. Glittery, shiny, and spotless. He would get to the club early and stay at the venue all night long.
During these evenings, he had tickets. He did not give them away in the hopes that people would show up. Instead, he charged for the tickets, thereby adding value to what he was offering.
Dude was a hard-core Narcissist and highly charismatic, so he "made friends" with just about everyone he met. As a result, his gigs were always packed to the brim for the first year. He wasn't really selling the band. He was selling himself, and he was THE most incredible thing, in his own mind.
What he did can't be done online. Body language, voice inflection, intrusion of personal space, and real-time interaction got him some incredible results.
But he changed drummers and bassists the way most people change underwear, so his lack of consistency probably caused him some damage. Today, he's a real estate agent.
I think that posting about a show online is about the same as getting flyers printed up and leaving stacks everywhere. They don't really do much.
