Official lessons - sight reading for a few years.

Then - the piano teacher started teaching chord theory and chord positions. That, I got hooked on. I realized the piano based Journey songs that were popular in high school were actually easier to play by learning the chords and figuring out the arpeggios that were being used. Favorite chords at that time were add2 chords. All the girls liked them!

Now, 20+ years later of pretty much faking it, using knowledge of chord theory; playing off of chord charts and in the right style with the right chord inversions and now muscle memory, I can hardly sight read anything more than a simple melody line.

Over the past 1/2 year or so, I'm slowly trying to get back into sight reading some of the classic piano tunes that I love. Pathetique by Beethoven has been my starting point. Still not very far through it.

All of my fake-playing is pretty much self taught, at least from a fingering of chords standpoint. However, once I saw Scott Houston on PBS 'The Piano Guy', I realized that's pretty much how I self-taught. It works great for playing pop tunes and playing in rock and country bands and so forth. To complement your sight reading abilities, I would highly recommend checking out his stuff as a practical way to break away from the sheet music when called for.

http://www.scotthouston.com/store/home.php

It will help you immensely along this path to study chord theory and chord voicings on the keyboard. Very often, in fact much of the time, the root shouldn't be the lowest note played. You'll find yourself being able to pick out voicings just by listening for what seems right with a recorded version of the song. I have to say that this is my most natural way of playing right now, not unlike Bob's picking capability. It becomes hard-wired. And in a band, it's danged fun!

Good luck. Just don't lose the sight-reading skills!

-Scott