I don't know of any TV-centric websites like what you're describing. TVwriter.com is probably the closest though I don't know the site that well so I can't speak to its helpfulness or lack theerof.
If you had a site that focused "developing skills," I think that could be very useful and probably immensely popular. There's a lot of great information out there these days. A lot of successful TV writers have taken to blogging and even a site that was nothing more than a central location for that information would be great. (Like a Whedonesque for TV writing.) The "finding work" and database idea is a little tricker for several reasons.
First is the legal aspect. IIRC, a writer recently sued a judge from a screenwriting contest, claiming that said judge stole their spec idea and used it on his show. While that might be an extreme example, accusations of thievery among pre-pros on the internet are not uncommon. So logging onto a database, filled with endless specs, could open someone up to a shitstorm of liability. I suspect anyone who works in the industry would be leery of that.
Next is the quality issue. I'm not sure what you had been planning but, if it's a place where anyone can upload anything, quality will probably be all over the map. There are some great writers out there who haven't found their way in yet. But there are also some not so great ones. With a database like this, I would think that you'll have to wade through a lot of less than stellar specs to find that hidden treasure. I don't see many people having the time or inclination for that.
The last thing, and I hope this doesn't come out wrong, is the need question. Obviously, the need is there for anyone looking to break in. But I'm not sure the need is there on the side of industry folks. There are already so many more writers than jobs in this town. Like, you probably have better odds of winning in Vegas than Hollywood these days. John Rogers has a whole post about staffing for his new show, in which he refers to "the writer apocalypse" and he's not wrong. 210 submissions for four slots. I'm willing to bet it's even crazier on the bigger network shows. (Joss probably needed an entire room for all the submissions he got on Dollhouse.) So when you're already being deluged by scripts from writers that either have a great agent, a recommendation, previous experience or all three, are you going to be at all willing to go look for more stuff to read?
That's not to say that it's impossible to break in.* People are looking for new voices. But I doubt that finding your way in will ever be as easy as hitting an "upload" button. Hell, staying in isn't that easy. You really have to be willing to bang your head against the wall until you break something. The wall, your cranium, every bone in your body, whatever.
Now with all that said, the prevailing wisdom in this industry is that there's no prevailing wisdom. So take everything I just said with a grain of salt because it's entirely possible that I'm wrong.
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* Read John August on why there's really no such thing as "breaking in."