Remember, learning is like a drug to the brain (actually, it is a drug). The best user experiences–combined with a clear path to greater expertise and the promise of more time in flow–are like a healthier, happier form of crack. One of the best examples of this drug-dealer model in software is Apple.
With iMovie, for example, the first one is free. But once you’re hooked, you find yourself wanting capabilities found only in the $299 Final Cut Express. You find yourself wanting, no needing to do things you never even imagined before you started playing around with iMovie. And for a certain percentage of users, even Final Cut Express will have limitations. Now you need the $999 Final Cut Pro or–for just a few dollars more, what the heck–might as well go for the whole Final Cut Studio. They’ve managed to teach you to want the most expensive versions of their products. Then they do the same thing with sound (Garage Band –> Logic Express –> Logic Pro). It seems Apple has figured out the optimum price points for their “next levels”, in order of FREE, $299, then $999.
But even if the goal is not to teach or inspire users to appreciate your higher-end products, just having goals to strive for is what matters. Whether the promise is that you can become a first-level moderator, a church usher, one who can use the RAW features of Photoshop, a CSS guru, a Sun Certified Business Component Developer, a double black diamond snowboarder, or a 3-dan go player… never forget that where there is passion, there is always a next level.