Love is an MMO under development that makes use of procedural algorithms - that is, code that generates graphics, levels and characters based on a set of parameters. It places a heavy burden on the programmer, but it means a group (or single) coder can get away with not having artists, designers and level builders. Which is a good thing, as there's just one guy behind Love. His name is Eskil Steenberg.
A basic example is the dungeon-building code in the first Game A Week, Wizkill. Using hard-coded rules, the game produces unique, random levels that resemble something a human could make, given the time.
So what makes Love particularly special, apart from its breath-taking visuals and natural-looking environments? From the Wired story:
Players can rearrange trees and boulders, reconfigure buildings, or hollow out new caves in hillsides. The gorgeous vistas are also subject to natural phenomena like erosion, thanks to Steenberg's tectonics system.
There's another MMO in development - Infinity: The Quest for Earth - that uses procedural algorithms to generate content, and was originally a one-man show. The difference is Infinity uses its algorithms to pre-generate its universe, rather than to constantly create and alter unique environments.