How much are you worth?

Generic stock photo poached from here.

I've been doing a bit of exploring of the job market lately (depressing, right?), and I've been seeing more and more job postings that request a salary requirement with absolutely no guidelines.

And that makes things tricky.

On the one hand, I don't want to put something so high that I'd be immediately disqualified for a position, but I don't want to sell myself short either. If I put down an expected salary and they were willing to pay much more for the position, of course they're going to offer what I asked for.

Or maybe even less.

I mean, I get that companies want to weed people out whose salary expectations aren't in line with what they're willing or able to pay, but wouldn't it make sense to at least post at least a range of what you're willing to offer with a stipulation that's it's based on experience?

Or, if what you're going to pay is set in stone, which is often the case, why not just include that in the job posting? In the current job market, I doubt you'd scare away all your applicants by low-balling them.

If anyone works in HR, I'd love some insight.