Other than computers, my kids quickly get bored with electronic whizbangs and other pieces of plastic. The Wii is good, esp on days when the weather isn't conducive to outdoor play (video games AND exercise, I'm all for it!), but it's not like they agitate to play with it.
Blocks, Lincoln Logs, Legos, and Matchbox cars, though? They won't put them down and fight over who can play with what. I spent hours yesterday putting a train track together with my youngest, and rolling his cars around on it.
Bought my oldest a gyroscope (really, just a fancy top) to play with this weekend. He hasn't put it down since.
One of my Nephews turned 3 a few months ago, and all four of his Uncles were on the floor playing with Noah’s new Matchbox stuff while Noah was content watching us haggle and eating some birthday cake...