Dumbells

The only exercise I know of for pecs using dumbbells are the chest flies. I use a lighter weight when I do those laying down. But, you can also do them standing up. It's hard to explain without me showing you, though. I learned this technique a long time ago. I also use machines and push ups to strengthen my pecs without doing any bench presses.

Theres also the lateral raise where you hold the dumbells in your hands and lift them up to the side so that you are making a T shape. This is also very good for the shoulders. Then theres the chest press where you lie down and lift your arms up. You can do this standing up as well.