If you’ve been online any time in the past few years, chances are you’ve seen–or signed–a Change.org petition. The site allows anyone to start their own online campaigns or e-petitions, which anyone can view and sign with an electronic signature of support.

The site asks petitioners three simple questions: Who do you want to petition? What do you want them to do? Why is this important? The platform, founded in 2007, allows everyday citizens to exercise their voice to gather support and affect change across a number of spheres–from human rights to the environment to health care.

Just recently, PepsiCo announced it would remove an ingredient that is used as a flame retardant in its Gatorade drinks. The move was prompted by 16-year old Sarah Kavanagh’s Change.org petition which gathered over 200,000 e-signatures. (Consumers beware: PepsiCo’s Mountain Dew product still contains the ingredient.)

We love when citizens exercise their voices to affect change in the public sphere, so here are some of Change.org’s most successful e-petitions to date:

Sprint: Improve Policies to Keep Domestic Violence Victims Safe
Over 175,000 people signed this petition, which asked Sprint to improve their policies to protect victims of domestic violence attempting to cancel or change their services to stay safe from their abusers. The human rights e-petition was started by Jane Doe, a domestic violence victim who remained anonymous to protect herself from her abuser. She launched the petition after Cindy Butterworth–her sister was a victim of domestic violence–convinced Verizon to change their policies.

USDA: Stop Using Pink Slime in School Food
Bettina Seigel started this petition on March 6, 2012, asking the USDA to stop using LFTB (Lean Finely Textured Beef) in ground beef going to schools. Just nine days later, the petition had garnered more than 200,000 signatures, and the USDA announced it would offer schools a choice of beef with LFTB or without the filler starting in fall 2012.

Prosecute the Killer of Our Son, 17-Year-Old Trayvon Martin
After the tragic killing of their son Trayvon, Tracy Martin and Sybrina Fulton started an e-petition to bring justice against the man who killed him. On April 11, 2012, the Florida State Attorney announced it would bring charges of second degree murder against the neighborhood watch captain who shot Trayvon.

MPAA: Don’t Let the Bullies Win! Give ‘Bully’ a PG-13 Instead of an R Rating!
The movie “Bully” attempts to bring to light the bullying epidemic going on in U.S. schools, a major human rights concern. The movie will now receive a PG-13 rating from the Motion Pictures Association of America (MPAA) after a whopping 500,000 people–including 35 members of Congress and celebrities like Ellen Degeneres and Meryl Streep–joined a Michigan high schooler’s campaign on Change.org. Katy Butler, a 17-year-old who was bullied in middle school, launched the petition after learning that the MPAA planned to give Bully an R rating–something she knew would prevent the target audience from seeing the film.

We’re also keeping our eye on a petition that has received 1.4 million signatures so far, one that urges the Boy Scouts to end the ban on gay scouts and leaders. At the time of this writing, the organization had plans to vote on the changes, further solidfying the fact that Change.org can be a formidable force when it comes to affecting social change and fueling improvements in human rights.

Have you ever started a Change.org petition? Share your stories in a comment below.