What should the limits be?

Where should the limits of free speech be drawn? Specific threats of violence including death threats I do not believe should be protected. They should be placed in the category of inciting violence. But what about symbols? At what point do vague references become inciting action.  According to this article, placing target sites on someone are what are meant by threats to law makers.

Dem planning bill that would outlaw threats to lawmakers - The Hill's Blog Briefing Room 

I do believe that what happened in AZ was a tragedy, but I'm not about to credit the actions of a mad man to the Tea Party affiliated web site.  If the word "target" would be outlawed, I'm sure that whatever word used to mean "focus efforts on" could be potentially construed to mean the euphemism for "target" and thereby also be brought under the umbrella of the ban.  If that were to be the case, then someone, presumably the courts, would have to discern the author's (or speaker's) intent. Something which the courts already struggle with.  That then leaves a ban being either a broadly covered unconstitutional infringement on 1st Amendment rights or a selectively enforced ban based on the political leanings of the enforcers or jurists.

Hence, I would lean toward no ban. Not that I don't want to prevent such tragedies that occured, but rather that I find the proposed solution to be more harmful than the problem. But I'm open to suggestions.