A.W.
puzzles are good. the 25-40 piece ones. Melissa and Doug make some beautiful ones. Works on spacial ability and problem solving and fine motor skills.
Duplo legos or even regular legos if he is good about keeping things out of his mouth and you feel he would be safe with them. My 3yo daughter loves them. Again, works on problem solving, fine motor skills, imagination...Legos are so fun.
Games - Hi ho Cherry Oh or Chutes and Ladders and Memory. Classic kid games that help with counting, taking turns, colors, shapes.
Books, books, books!!! Did I mentions books? LOL
I am not big on the electronic educational games - leapfrog, tag or zippity, but people do like them. I am just kind of weird about that stuff and won't share my views on it. But my mom got my daughter this little laptop computer thing with Little Einsteins on it. I was kind of not happy about it and it still isn't my favorite thing for her to play but It has about 15 learning games such as letter recognition, counting, what comes next, etc....and I can say that my daughter really likes it and for what it is, it seems to have some educational value. But I don't let her play with it much....special times only.