While I'm not a huge gamer, I do play occassionally, and Magic is a favorite of mine.
I recently started playing again, and found a nifty little infinite mana combo. Really simple. It's based on an ally deck, so you need to have sufficient allies in there.
It works like this. Get a Harabaz Druid out with a Crab Umbra on it:
You also need 3 more allies. Any ally will do. You can even use changelings in some formats.
Tap the Harabaz Druid for UUUU or as many allies as you have. Untap it for UUU. Rinse. Repeat. Infinite mana. Make sure to have enough mana to untap the Druid before you tap for any other color than blue.
Now, drop an uncounterable Banefire on your opponent:
It's pretty simple to pull off, and I can very often get it off on turn 4.
Cheers,
Ryan