I've talked with lots of biz/MBA people, as well as serious VC and angel investors. In fact, I used to work for a VC firm in silicon valley.
I know you think your idea is original. You can feel it.
It's not.
(reread those last two sentences until you get it into your head)
Here's the common sentiment about "not telling people about your idea": If your idea is SO EFFIN' SIMPLE that upon hearing it, I can go do it myself with success, your idea is worthless, because if really was that simple, someone would have done it already.
You may think "yeah, but in this case..."
No. Stop. Trust me.
The reality is, your idea might very well be a "good idea". I bet it really is. Would totally be handy. Would work. Would be popular. That does NOT mean it would be a good business. So, yeah, by keeping the cat in the bag, you're making sure no one else does it, and if you ever do it, you'll get the notoriety, but the reality is, you could post the idea in every forum on the planet and you likely wouldn't be costing yourself a cent.
So, if you want to do it, do it. If you need some help to do it, get help. But for the love of christ, don't sweat telling people about it (ESPECIALLY when it's something as trivial as a website. You think crap like Myspace was a "secret"?)
We're all waiting for the link!