Dear Esther is currently in the Steam Sale for the princely sum of £1.74 (or equivalent in other currencies). (I had been thinking about trying it for a while, but this price was the deciding factor.)
Buy it. Download it. Play Experience it. (Especially if you're not the sort of person who likes computer games.*) It'll only take a couple of hours, but it shows just how beautifully and thoughtfully stories can be told through the medium of computers. It's like being inside a poem. A melancholic, surreal, poem. (Or maybe that's just me.)
Oh, and if you can't play it in one sitting, remember to save -- PC key F6 -- before quitting. It doesn't prompt you to do so, which is the one major interface flaw.
* If you're someone who has never played modern computer games, look at the control keys (under Options) or you'll be very confused. For the rest of you, it's WASD + mouse.