This is a new discovery for me. I used to think it wasn't all that great back in the day, but now I've come around and seen it's potential. The one mana it produces isn't super-spectacular, but it's pretty cheap as far as mana rocks go. Its true potential lies in the fact that it can draw a card at instant-speed, which is never a bad thing. Use it as ramp to get you where you want to be then break it for the card you need.
This may seem like an odd choice, but give me a chance to explain. Let's say you've got a hand of six cards on turn three. Three cards are cards you want and the three you've drawn are complete crap in your current situation. With this card, you can get rid of those cards and try and draw something better. Now, many people are going to be turned off by the random chance aspect, but try looking at it like this: the cards in your hand are bad, but the cards you draw might be better. If you're in a bad spot, there's no reason to not gamble. And unlike, say, Winds of Change, you get to keep any cards you want, which puts you at a more advantageous position.
This will usually be a free turn for you since not many players are willing to lose half their life to stop it. Either that, or it's going to hit someone for half their life. Either way, you win.
Sins of the Past
This card surprises so many people. Remember that Damnation that you used a couple turns ago? Well, now you can use it again and solve more problems. It works in so many situations and it's great. I've never been sad to draw this because, even if this is triple the targeted card's cost, it gives you access to something you normally wouldn't be able to in a black deck.
It's a Rampant Growth on cocaine (and cocaine accessories). It costs four, but it gets you two untapped lands. Two untapped lands. This may only be able to get forests, but you can get shocklands with it, so it's actually a lot better than it seems. Brings you from turn four to turn six in one fell swoop.
Remember that time someone swung at you with a bunch of tokens and you died? Sudden Spoiling remembers. This counters so many creature-based problems it's not even funny. Need to solve a Memnarch/High Tide/Palinchron combo? Use this and Memnarch is useless until the end of turn, making that High Tide a complete waste. Best part about it is that there's very little that can be done about it due to split second. Great one-shot solution.
Price of Glory
If you're like me, you tend to want to stop people from having shenanigans. This stops shenanigans. No more counter magic, no more "end of turn" happenings (at least not without a huge price tag). It's just like nature intended.
It's a backwards Sygg, River Cutthroat! It hands your opponents some serious card disadvantage, especially if you've got got some sort of repeatable damage system going. Unfortunately, it doesn't trigger on life loss nor does it count cumulative damage, but it's still a nice card that will probably make someone unhappy.
This little guy is a great ramper. He's two Rampant Growths on a stick, which makes him a great blocker (block, become two lands). Just a really good creature for decks with green.
It's a better Boomerang. Even though it costs one more, the split second makes it well worth the extra mana. It's especially fun to run against control decks since most control players get really upset when something happens that they can't do anything about.
That's my list of things you should consider when making your next EDH. I'll have more at some point I'm sure.