Well, I don't know... I've tried quite a few things. First, I replaced the wire to the speaker with a high gauge wire (thinner and twisted, not solid core) because I was worried maybe not enough power was being generated. No luck. I also replaced the TEA chip and a few capacitors (didn't have enough of each size to replace them all) but that doesn't seem to have helped either.
Next, I took a look at the adapter. I thought - okay, maybe the adapter just isn't functioning... but no, it works. I used it with some patch cords to connect to a small radio with the right plugs and my iPod played music just fine. So something is wrong with my circuit.
Based on past experiences with this book's exercises, I knew it had to be operator error. Something small and simple to overlook... but I checked all my resistor values, checked where every wire was going (positive or negative voltage), double and triple checked ever TEA chip pin to make sure they were all wired properly and none were ignored... and I'm getting zip.
Is it possible that the iPod via the adapter via the breadboard just cannot power this 8" speaker? Suggestions welcome, but I'm probably going to go ahead and ship to exercise 31 and leave this one alone... I don't have to take it apart for exercise 31, so I'll give it a break and see if a light appears in the sky with the answer.