France and Jean-Marie Le Pen
Why he has his admirers

Well, a lot of it is that a lot of Frenchpeople (like a lot of people everywhere) are bigots and morons. In the US, these people are mostly channelled into the extremes of the two parties, and rarely cause serious trouble. But in a multi-party system, the bigot and/or moron vote can cause trouble. Le Pen, as has been noted, didn't actually do any better in the election than he usually does, but the Socialists underestimated their own weakness and let Le Pen slip in.

To be fair, Le Pen reflects a lot of real concerns -- crime, unemployment -- that the French political mainstream was ignoring. The beauty of the American political system is that when the mainstream parties get out of touch and third parties spring one of the big boys will usually absorb it and its policies. The Republican ascendancy (in Presidential politics) of the seventies and eighties, and its current Southern dominance was built on George Wallace's supporters. Clinton took over Ross Perot's deficit-hawkism, and then Gingrich took over most of the rest of that agenda.

But as long as France's two major parties could continue to draw relatively small numbers in general elections and still know one or the other would win in the end, they didn't really have to address that. (I just want to point out that you could reject the two big parties without voting for Le Pen -- and a lot of Frenchmen did.)