Awright, I'm going to chime in here just because this is on my mind at the moment, and I think I disagree with everyone who's posted.
Over the last couple days I've gotten off the fence: I think there should be a no-fly zone. (Sending ground troops and arming the rebels shouldn't be necessary IMO.)
This is above all because it's getting clear that if this thing is allowed to play out on its own, Gadaffi will win. On this basis, I think it's both morally imperative and a matter of our own interests that we do something.
On the moral side, we're currently standing by while a repressed people, fighting for its own freedom, is slaughtered. We had to do this in '56 and '68 becuase intervention would have started WWIII, but in this case we're hardly dealing with the Soviet Union. Remember all those decadent lefties at the beginning of the Iraq war (which I opposed) who said we should let the Iraqi people themselves take care of Saddam? The obvious rejoinder was that that would never happen. But now it IS happening - those lefties should all be supporting intervention.
As far as our interests are concerned, remember that Gadaffi supported terrorism and was actively seeking nuclear weapons. The 'deal in the desert' dealt with that, and got Western companies into Libya, but now the chorus of Western governments is delcaring Gadaffi an illegitimate ruler, and putting sanctions in place. Once he gets control of his country again, is he really going to deal with us as before? Heck, he could well go back to supporting terrorism for revenge for what we've already done.
Yes there's a good chance of mission creep, and yes, the Arabs will come up with conspiracy theories to blame us for any negative aspect of what happens, but they're going to do that whatever we do. This isn't Iraq: there's an opposition which currently holds a substantial portion of the country actively at war with the state calling us in. And yes, whatever succeeds Gadaffi might very well be as bad as him, but it can hardly be worse, and it would be favourably disposed to us.
Some food for thought...