I agree about making certain that the meat is tender and juicy. Little ones are still developing jaw strength and it's easy to overestimate their ability to chew something.
Also, if he likes pasta and sauces, it's very easy to mix ground turkey or beef into the sauce, or to puree beans into it. Stews are a good idea, too.
Mahi Mahi is a favorite fish around here (though now that I say that, I realize that we haven't had it in quite awhile) -- when my now 7 year old was little, he thought it was chicken (though it's lots easier for little ones to chew). Dh also makes fish nuggets.
I add eggs to oatmeal, and my guys love scrambled eggs. A friend likes to take bread, put it on a cookie sheet, cut out the center with a small cookie cutter, and crack an egg into the opening. She then bakes it in the oven until it's done. I've done this one or twice, and it's yummy. We don't do it often because we try to avoid a lot of wheat, but if your LO isn't sensitive to wheat or eggs, it's a great high protein snack.
Amanda and Dh, ds 09/00, ds 08/03, ds 10/05, and ds 05/08, and 3 :