When my DS8 started a new preschool/daycare at 3 I met the teachers and they stressed that they did not push academics and were more play based. I remember worrying about this, thinking he would somehow be behind the curve when compared to all the kids going to more academic oriented preschools. Then I heard reports that studies were showing more and more that children in play based pre-school did better later on in school. (I also remember my DH used to quote a report he heard about providing a "toy rich environment" as we looked around our excessively cluttered family room

)
It is easy to fall into the trap worrying whether we are doing enough for our kids, but I worry that we may be doing too much too soon. Play is so important to learning.
We did do a lot of what spiritedmama mentions - reading, zoos, museums etc. And he showed an early interest in computers (at 8 months old he wanted to sit on my lap and press the keys and watch the screen) so we spent a lot of time at the library playing different games.
Ultimately, the best advice I could give is to follow your DC's lead and your own feelings.