Checks and balances, together they make up a crucial part of this puzzle we call life. It is a full fledged system of being, not just an ideal. In a word: KARMA. The idea that what goes around eventually comes around, and what you put out to the universe you will ultimately receive in return. It's actually a very beautiful idea in theory and in practice it is even better.
Even for non believers, it would be a fantastic system to follow because it helps to keep our actions in check when dealing with others if you can understand the concept behind it. Doing unto others as you want them to do to you, treat others how you wanna be treated, etc. What's not to like about that? The system promotes love, tolerance and peace at its very core.
Three things I know I could use a lot more of. Ignore for a second, the fact that karma is thought of in many capacities, as a religious tool. It does come from Buddhism, but that is totally beside the point. Let's get back to the fundamentals of karma. Think of cases in your life (or hell, in other people's lives even) where you have thought, "Wow, ok...so I deserved that." or even better "HA HA that guy got owned. Nice, cause he totally deserved what he got!" Well, that is karma at it's best right there. Than, on the other end of the spectrum, you may have something awesome happen to you and think to yourself "Man its about time something like this happened to me! I'm a good person, I deserve good things too." Karma again.
Karma has even taken a fairly prominant role in the mainstream lately with more and more being published and read (like you're reading right now and I am writing right now), and even TV getting in on the act with shows like "My Name is Earl", which has been on multiple seasons, and is centered around a guy trying to correct his karmic balance by making up for previous misdeeds. Not only does it get the word out there to millions that just needed the right forum to see what its all about, it also really makes for great TV.
In the end, the only big concpets there are to think about when dealing with Karma is this: You always get what you give, Karma ALWAYS catches up to people, even if you dont see it first hand, and practice makes perfect - the more you try to actively do good deeds, the easier it gets and the more routine it becomes. Good deeds=Good Karma. Good Karma=Happy Life. So spread the word far and wide. Remember the message is love, peace, tolerance, and getting one's just ends. Namaste!