There is no card type in Magic more important than Land. Every deck you've ever made (barring the one or two exceptions) has had Land in it. I'm not here to argue about how the Land card type should be voted for in YMTC4, as this post will be posted after the voting is over. I'm just posting facts.
1) If a land only taps for a single color of mana and has no other abilities, it is Basic. In fact, just having a basic land type lets that land tap for a specific color of mana. These are (as the name says) the most basic cards you need to play Magic. These are given away to anyone playing a draft or sealed deck so you can actually finish your deck. Some people even say that Island is the most powerful card ever printed. (And, yes, I linked it.)
2) If a land taps for a single color of mana and also has a secondary ability, it needs a drawback. The most common drawback is entering the battlefield tapped, although there are a few cards that have different drawbacks. The uncommon threshold lands from Odyssey deal you damage, and the rare Kamigawa lands are Legendary. Some of the most powerful non-basic single colored lands are the artifact lands from Mirrodin. Their only drawback is the same as their advantage: they are Artifacts as well as Land.
3) If a land taps for a single colorless mana, it can have a secondary ability or benefit without having a drawback. There are many examples of this, from Mishra's Factory to Rogue's Passage. These are your utility lands. You use these as a hard to deal with source of advantage. They add mana to your mana pool if necessary, but offer so much more.
4) If a land taps for two or more colors of mana, it needs a drawback. Some of the most expensive cards to obtain in the game are the original dual lands. The reason they are so expensive is that they give you access to more than one color of mana from the same source with no drawback. Every other land printed that taps for more than one color of mana has a drawback. When Arabian Nights was released, there was a card called City of Brass that could tap for any color mana, but dealt you 1 damage for the trouble. In Ice Age, where lands were printed that could give you two colors of mana, their drawback, again, was pain. These lands were lovingly called Painlands and every player took their harsh punishment and smiled as they cast a spell they wouldn't be able to otherwise. And so it goes... the drawbacks shift, but the two main competitors are entering the battlefield tapped and taking damage.
5) If a land taps for more than one mana at a time, it needs a serious drawback. Urza's Saga was broken. We all know this. One of the big reasons it was too powerful was its land. The rare land cycle has Tolarian Academy and Gaea's Cradle, two easily abusable mana engines. While they were Legendary, they were both way too powerful to be printed (especially the Academy) and produced too much mana for the drawback. Another powerful card is Mishra's Workshop, which gives 3 colorless mana that can only be used to cast artifacts. It may seem like a harsh drawback, but 3 mana is 3 mana, and you can use it as soon as the Workshop enters the battlefield. Mistakes like these help us understand what can be done with a land before it's too much.
These are the rules of lands. I know that Maro has said countless times that restrictions breed creativity and I'm excited to see what we can do with Land if it wins. I guess we'll find out on Monday.
After all that, my card for today falls within the confines of the rules and I will post it for your viewing pleasure.