Now I like to think of myself as a passingly good DM these days. What gets me is having to draw maps, lots of maps, before I can really write my adventures. Also, I have a really good idea what's going to happen at the start of a campaign and where it's going to end, but somewhere in the middle the creative juices starts to fizzle out on me.
This has suddenly started to change as I turn my attention towards Nicolas Logue for inspiration. Nicolas Logue is perhaps the best pulp action adventure designer I've seen. He's written two of the best articles in the new Dragon magazine as well numerous adventures - namely Chimes at Midnight, Quoth the Raven and Hell's Heart, all easily the best written Eberron adventures I've ever played in or ran. While he primarily writes Eberron stuff, at least from what I've seen, he comes up with amazing scenarios for the player characters to be in.
Using his type of adventure layout for inspiration I've come up with much better scenarios for my IK game. Suddenly the use of terrain is important, I stop thinking about what works and think about what's cool instead and see if there's some way I can fit that in. I recently had my PCs investigating a depleted coal mine infested with Cryxians, instead of just having them come across the slayer I had it smash through a wall behind them in a shower of coal dust and rocks and glowing necrotite. I've had a gun mage using a rope line pirate-style (one foot in a loop, one hand holding the rope to keep stable, and going up at a fast rate - you usually see it in pirate films where someone whizzes up to the crow's nest) while the PCs race up the stairs to keep up with him to the top of a clock tower. Of course he kept shooting them on the way up, then the clock tower exploded, it was awesome.
So now I've started to do adventures with a few new rules: ignore the recommended number of encounters, if you're short a few or a few too many, it doesn't matter; make every encounter something to remember; put the PCs in new and interesting situations constantly; and make sure it's cool.