Why do zebras have stripes?

I was watching a TV show today prior to football with Bill Hanna and got to wondering why zebras had stripes. If anything to me it seems like they make the animals stand out / more obvious to predators.

From what I can tell from brief reading on several websites there aren't many explanations that make good sense to me, but some of the leading ideas include.
1. Form of recognition between animals in the herd. My thought is this is plausible, but why would such outlandish stripe displays be so rare amoungst herbivores - most are just brown?
2. At key point when lions pounce on the zebra herd the swirling stripes can cause just enough confusion to help survival - especially to make it harder to find/track the younger zebras as prey. This to me seems plausible - although wikipedia notes that field observers don't notice any particular confusion amoung lions in the hunt.
2a. In a tight herd it makes it difficult to isolate individual animals, they all blend together.
3. Simple camoflauge. Apparently lions are color blind and the white black stripes would not be noticed (Like orange hats and deer), and the striking black/white color isn't such a big deal for primary hunting times of lions - dusk/dawn/and at night. I can't speak to this other than no other animals have adopted coloring close.
4. thermal effects - black absorbs heat, white repels heat, and the difference in the coat colors creates micro-air-currents around the body creating a cooling effect. Net effect a large amount of heat is deflected, and cooling current produced near the body. I would've never thought of that potential. Who knows - kindof strange idea, but maybe?
5. Visually the stripes serve to confuse the tse-tse fly. I guess if it reduces the load of flies on the animals it might have some merit, but would it be enough?

None of the answers are really very satisfying if for no other reason than no other similar animals seem to find much value in such crazy coats.

Part of me wonders if the stripes are a by-product of something else going on, or a byproduct of something that used to be advantageous that now is just leftover from history.

Heres some links with ideas:
story 1
story 2
story 3