I have a couple of shelves of poker books, including all of those mentioned so far except Harrington's cash books.
My highest recommendation for cash games is Professional No-Limit Hold'em and for SnG's I like Moshman's SnG Strategy. The latter is geared more to single-table SnGs but much of it applies to any tourney situation. I'm currently split between both of these books and have finished neither, but both are excellent. I started reading PNLHE when I was still playing cash a lot, but then switched to tourney/SnG play and started Moshman's book.
Sklanksy/Malmuth books are generally more advanced and dry compared to the others mentioned, so beginners typically won't get as much from them. I think they're a lot more useful upon re-read and after your game improves.
The books that Ed Miller writes or collaborates on are usually good too, including his latest eBook which I hear is a bargain at $99 -- and if you think that's expensive, there are lesser eBooks by others that sell for several hundred. This'll probably be my next poker book purchase.
