From the FAQ:
"Glitch is a web-based massively-multiplayer game which takes place inside the minds of eleven peculiarly imaginative Giants."
A browser-based side-scrolling Flash MMOG with no endgame and rather attractive art, using a free as in beer model instead of F2P (but not win) so common nowadays. Some paid content is available -- mostly avatar customization, I think, but also you can buy an optional $30 yearly subscription.
Skill grinding appears to be a large part of the game, and seems to be based on time not skill use. The brains behind it (one Stewart Butterfield) also produced "Game Neverending" some years ago before founding Flickr and then selling it (Flickr, that is) to Yahoo.
Note that all this is based on their web site and not actual gameplay, as I typed this up as I was waiting for the overloaded servers to send me my account credentials, some hours now after I first tried to register. Hrm, maybe I shouldn't tell you about it...yet...
edit: I've now been playing the game for a couple days, and mostly my above comments stand. I still haven't found any hint of an endgame, although there has been some foreshadowing of an group named The Rooks that eventually become some sort of an enemy down the road. The skill system is something of an EVE-lite style, although with enough play all skills seem to be achievable eventually. Skills tend toward resource accumulation and crafting.
Avatars spend two resources, mood and energy, in order to accumulate items and experience: mood is not required, but when it runs out penalties accrue; energy is used to do almost everything and when it runs out, the avatar has some sort of minor death penalty that I haven't seen yet. Both are easily restorable through a variety of means, including food/drink and meditation, and both fully restore every 24h of game time (about 4h of real time).
Two things I've found so far make this a standout from a gameplay perspective.
1. There is very little violence and a great deal of attention is given to making "Glitch" a low-competitive, friendly gaming environment (there seem to be two interpersonal emotes: hug and kiss; players are encouraged to tend to the needs of trees and animals). There is some mild PvP but all that I've seen is the sort of thing you would find in "LEGO Universe" and similar younger-aimed MMOGs (e.g. races).
2. There is a relatively (for the genre) extensive pseudo-religious system, involving eleven demigods who the players make sacrifices to in exchange for boons. This is not an optional system, in order to progress more than about halfway through any set of related skills hierarchy it is necessary to gain and use tokens of appreciation given exclusively via this process. There seems to be an extensive backstory/cosmology involving the demigods but it's presented in a very low-key (nearly no-key) manner.
The tone of the game is a fairly straightforward mix of spirited adventure and mild surreality, with some rather irreverent and self-deprecatory humor, somewhat reminiscent of "Kingdom of Loathing" (and I wouldn't be surprised to learn that that game is one of the designers' major influences). There's a lot of sly tongue-in-cheek humor that probably would go over the head of younger players, although a couple of the jokes gave me a good chuckle.