i thought the end effect in Book of Eli was the sun? i remember the phrase 'the sun turned on us' from watching it (admitedly once, and i am glad that the book the film was based on, had the wizard of oz be his book)
i am legend, while interesting, the whole end i did not like (i saw omega Man and to be honest, the whole of i am legend bugged the hell out of me for being a sort of preachy version of Omega Man imho) but i did find an alternate ending they didnt publish (at was on some of the special editions, and got uploaded to utube) that made a whole lot MORE sence to me (and was a lot more like omega man to me lol)
12 monkies is a lot less confusing if you grew up on things like it. like Brazil and Monty Python lol.
and there are a LOT of older or smaller movies for apocalipses you can find that are confusing / good.
for one thats about the (freezing) end of the world, look for the older version of Quintet http://en.wikipedia.org/wiki/Quintet_(film)
but generaly, end of the world movies make me yell at my screen. ether because folks are dumb, gready or generaly just make me want to smack them one XD