One of my favorite things to do with my kids is to play around with image search. We’ve got a couple of laptops that are always around the house and frequently I’ll grab one and ask one of the kids what they want to see pictures of.
My youngest daughter Kate is 2 years old. She will automatically say puppy or kitty or sometimes Einstein (she likes Baby Einstein). I then type puppy or dog or cat or "baby einstein" into either a Google Image Search or a Flickr tag search (sorted by interestingness) and up come tons of thumbnails of what she is looking for. She is delighted by the searches and will point to the thumbnail shot of the dog or cat that she wants to see and we open that one up and look at it together.
I’ll also suggest stuff to Kate that she might want to see. I’ll ask her if she wants to see a giraffe or ice cream or whatever and she always says yes. It’s a great way to teach a two year old more words to describe their world.
The other kids enjoy looking for images as well and with my oldest son Jack, who is 6 and learning to read, I’ll actually have him try to spell out the words that he wants to search for.
Keep in mind that image searches can turn up some pretty random stuff sometimes (some stuff which isn’t always the best for kids to see), but for most generic searches you are overall pretty safe.