Here are links to sites that deal with issues that are important to me. PLEASE visit them if you have time, though it sounds very cliche, some of them can help you really "make a difference".

Animal Rights

People for the Ethical Treatment of Animals
Homeless Pet Adoption & Rescue
Petfinder.org: Search for the perfect pet to adopt from a local shelter
Vegitarian, vegan, and cruelty-free products on the web

Environment/Conservation

Save acres of rainforest in one click - for free!
Aark Wildlife Center

Other World Issues

Give food to starving people in one click - for free!