Good Omens, Neil Gaiman & Terry Pratchett.
Highly effective, an amusing, fast-past and very engaging book. Plays to both writers strengths, and offers a good deconstruction of basic Christian mythology. Deconstruction not just in the sense of taking apart, satirizing, reworking and altering, but also in putting them together again, so that in the story measures like a prophesied apocalypse and omniscient benevolent God are meaningful and interesting. All told that's quite an accomplishment, and the textual-bending nature of the work makes it even more fun.
All told it feels a lot more like Pratchett than Gaiman, but a Pratchett that's in top form of control over language and character detail, and Gaiman's influence in the reconceptualized norms of heavenly theology is pretty clear. Overall a productive collaboration, a good working of the wonderful premise: the Antichrist is raised wrong, and doesn't want to bring about the apocalypse. Shines through effectively because of strong characters, and a very good depiction of friendship across the isle.
Similar to and better than: Terry Pratchett's Small Gods
Similar to and worse than: Mike Carey's Lucifer
As well, in the two-for-the-price-of-one category, Gaiman's Coraline. Much of my thoughts on this have already been expressed--that Gaiman is incapable of writing a bad story, but at time he aims rather lower than he's capable of, particularly with his YA material. Coraline is better than most of this pack, being incredibly creative and highly creepy. Where much of the time he offers a kind of brilliant narrative midrash to existing mythologies, poly and monotheist alike, here he builds his own set of magics and supernatural forces, making an intimate exploration of one home and the whole world that folds into it. Certainly it's an accomplishment few authors would be capable of, but it also seems peculiarly pointless in some ways--after a certain point it's the pilling of weird and creepy details for their own sake. If characterization had been a bit more complex maybe that would have carried the distance, but as is this is a very talented work that still doesn't rank anywhere close to what the author is capable of.