I just got an email from one of my players, a guy whose Elf Ranger has been playing since day one of my first 4e campaign (now 15th level).
Since we started playing, the character in question hasn't really had much of a background more than, "I'm an elf who likes the forest . . . and shooting things, I guess."
Anyway, I am suddenly greeted with a fully fleshed out story---in three acts, no less---about his spiritual awakening and arduous quest to bind himself with the animistic spirits of his people. The tale introduces a full family history, complete with a sister and a dying father straight out of King Lear, culminating in a harrowing ritual which bestows the mantle of "Seeker" upon the character---the sole elf of his generation chosen to control the primal spirits of the Wild.
He humbly requested that I allow him to change his class from [min-max/numbers on a page] Bow Ranger to [heavy RP/living, breathing character] Seeker between sessions---all from a single reading of the article and a few minutes with the character builder.
I'm a very, very happy DM right now.