G.K.
My niece is 6 and got the Leapster Explorer, and she LOVES it! It has the touch screen like the other 2, but the games practice writing, etc. I disagree about the damage is could do developmentally if it's used as an educational tool. Just like TV.
TAG is another good one for helping with reading, and the books that come with it can be read at any time with or without the TAG pen. So, you could still sit down with him and read with/to him.
I LOVE Leap Frog!! Their products have boosted learning in this household! From the fridge farm teaching animals, matching and sounds to the Alphabet toy teaching letters and sounds to the Word Whammer teaching about 3-letter words and lower case letters... I love them all, and I'm certainly NOT a lazy parent!