Two words- "Thomas" and "trains".

Our grandson turned two at the end of August, and he LOVES anything to do with trains, especially Thomas and friends. His favorites are the wooden ones that connect with magnets.
I've always loved the Radio Flyer toys, and when our grandson turned one, we bought him the little sit and scoot trike. He has outgrown that trike, so we bought a bigger one for him this Christmas. Here is a picture of it:
It's the sounds and lights Radio Flyer tricycle, and is built on the frame of the original Radio Flyer trike. It's very sturdy, yet lightweight. This will be his first trike with pedals.

I think he's really going to like it!
There are turn signals on the front that light up and sound just like the real thing.
Our grandson is also in love with Snoopy and Blues Clues. He's getting a big, stuffed Blue dog for Christmas. He also loves puzzles, books and Megablocks.
Really, there are a ton of toys that little boys love! Other favorites of his:
trucks and cars (Melissa and Doug make some wonderful wooden ones)
sandbox and sand toys
bath toys
Play-Doh with cookie cutters
coloring books, crayons, markers (washable!)
Even clothes can be a winner for this age-group. I've never seen my grandson more eager to get dressed than when he knows he gets to wear a shirt that has a picture of Thomas on it!
I'm not a big fan of a lot of the electronic "educational" toys for this age group.