A play kitchen has been a staple for both my children as well as every child I've ever babysat, including boys. You can get one with lots of neat doodads (ours has a little coffee maker, phone, fridge, oven, microwave, and the stove has two burners, one of which makes little boiling or frying noises depending on what pan you put on it) and lots of plastic food to go with. I have seen countless children play for hours with this thing. You'll also need plastic plates and cups, etc...a lot of the kitchens come with some stuff.
Right now, my 2 and 1/2 year old likes doing flashcards...letters, mostly, but some shapes and colors...and I don't know why, but she just really likes them. She likes books, puzzles, blocks, and tiny little things (polly pockets, littlest pet shop...so whatever the boy versions of those are!)
She also likes to play with Little People stuff.
**As someone Sherri G also mentioned, we also have a HUGE set of GeoTrax which my children both adore, but it absolutely takes parental help at pretty much all times. My seven year old can just now put the tracks together, but she still can't set it up so it all connect in one huge circuit. Also takes a TON of room...even when storing, I had to buy one of those gigantic totes to put it in...the REALLY big ones. If you are going for a train, I would really recommend something smaller.