Where can you lobby for the ethical treatment of animals?

Pretty much anywhere, but in order to keep abreast of current issues facing animals and what legislation is being introduced, I suggest you check out the websites of the American Society for the Prevention of Cruelty to Animals (ASPCA) and the Humane Society of the United States (HSUS). These organizations are well-established and recognized, and are not radical like PETA. You can subscribe to the ASPCA and HSUS like I did. You'll receive email messages from them informing you of new legislation and how you can help. It's a great way to stay informed and feel like you're making a difference.