Here's a better combo. It requires FOUR cards but you could definately build a deck around this combo:
-Birds of Paradise (or Quiron Elves) - You need a creature that can potentially tap for blue mana.
-Intruder Alarm - If you don't know what this card does, it makes it so every time a creature comes into play, all creatures get untapped.
-Shrieking Drake - It's a 1/1 Flier for U. When it comes into play, you have to return a creature back to your hand.
With these three cards, you can tap the Birds of Paradise (or Quiron Elves) and play the Shrieking Drake to untap your Birds, as well as all your other creatures, and then have it return itsellf to your hand. This allows you to untap your creatures as many times as you want, as long as it's your turn.
Now here are some potential FOURTH cards for the combo:
-Another mana producing creature: Keep playing and returning the Drake for infinite mana.
-Any Tim (Prodigal Sorcerer, Rootwater Hunter, etc...): Infinite Damage to win the game.
Also, this combo requires only two colors, so you can make a Green-Blue control deck, countering stuff until you get out this combo for the win.