The Llanowar Elves card dates all the way back to Alpha in Magic. There is a reason this card has been around so long. It will work in pretty much any deck that incorporates green into it.
For a single green mana, you get a 1/1 green elf, which you can tap for an additional green mana. I have used Llanowar elves, or Lando, as I call him (along with his brothers Loyd, Llmar, and LeVar Burton), the entire time I have played Magic. While not the best of the elven mana ramps, he is still cheap and can help increase your available mana. Have clones of Lando? You could have 3 creatures and 6 mana at your disposal by turn 3 with these dudes.
Unlike our other Card of the Day entries, there really aren’t any in-depth strategies or decks that revolve around Llanowar, but that is because he works so well in so many green decks. I love this card, and Lando will always be a part of my green elf deck.