The term is "courtesy flush" - treat your toilet(/neighbors/roommate/husband/etc) to one once in a while. But I'm sure you've learned that already.
Really, and I know you're probably way past this point, but take that plunger and have a go at it. And I mean, a serious go at it. Give it several minutes. Like, keep going until your arms feel like they're going to fall off, and at the point, plunge for another few minutes. I still maintain that there are few of a toilet's ills that cannot be solved by having a good go at it with the toilet plunger.
But yeah - seriously, plunge like you've never plunged before, if all else is failing. And like someone else said, 3 hours after your original post (or IMMEDIATELY after you've decided to stop trying and yet cannot fix the problem), call the plumber.