Blizzard has announced a savory selection of rewards for folks able to draw their colleagues back into the folds of World of Warcraft as part of its "Scroll of Resurrection" initiative. The magic parchment works like this: If you manage to get a former subscriber to become a current subscriber, you'll net a faction-specific Spectral Mount. Your recidivist friend actually gets the better deal, netting a free upgrade to the Cataclysm expansion, a free server transfer and an instant boost of one of their characters to level 80.
You can check out the terms and conditions on Blizzard's site, but we have an extra requirement to place upon you: Don't be creepy about it. There's probably a way to approach your friends with this proposition without sounding all culty. We suggest you really try to explore that method.