One of the most common questions I had in my years at the store was, "What's the best/safest toy for my puppy or kitty?" Here are the four that I recommend the most, and all are great for the adult pets as well:
For Dogs :
1) First is the Classic Kong toy. It is extremely durable, and you can put treats in it to keep the dog occupied. For hours of puppy fun/frustration, spread the inside with cheese whiz or peanut butter and freeze it over night. This is also a very safe toy to leave with the dog in a crate. Remember, NEVER leave alone with your dog toys that have squeakers in them or parts that could be easily chewed off.
2) Another great product is the Booda Rope. Also very durable, and the frilly ends are great for flossing the dogs teeth. The company even has a Fresh N' Floss style!
For Cats :
1) First up is the Cat Dancer. It's been around for years, and whoever decided to market some simple cork at the and of a bouncy wire was right on the money! Cats of all ages love this product.
2) Again, cats seem to appreciate the simplest, and "best-on-your-budget" toys. Try the sponge golf balls that you should be able to find at most pet food and supply stores. When I started at my store, they were a measly quarter, and they couldn't have increased that much, right?
And remember, the more toys your pet has, the less likely he/she is to invent toys using your household items as ideas!