I launched a little social site dedicated to gamers in the fall, and it hasn't picked up any traction at all. It never received any press coverage or anything. The blogs I contacted never responded to any of my emails. I've tried getting the word out through gaming forums, but that didn't help. I went back to my old WoW guild's forums, and they didn't even seem to care.
I feel like my site hasn't even been looked at to be given a fair chance, so I'm hesitant to call it a failure. Though, another part of me wants to think it was a stupid idea with bad execution. When do you know when to move on to a new project?
A few months later I do a Google search to see if anyone had said anything about it and lo and behold, one of the notable poker training sites had done a full hour long video on how to use ALL IN Expert to improve your game. They had found out about the software, either because of my initial marketing or just randomly through Google, and wouldn't you know it: they found it useful. Now its downloaded a dozen or more times/day. Not much, but who knows what would have happened if I had kept promoting it.
It can be hard to tell when to give up and when you should push just a little bit harder. When I stopped working on it, I started working on a new project, Domain Pigeon, which will likely prove to have been a good decision.
My 2c: Leave your site up, make a few changes every now and then, keep promoting it even if only an email or forum post every few days, and re-evaluate in a few months. There's not really a good reason to take it down, even if you do choose to devote your time to something else.