I checked out whitehouse.gov and their list of existing petitions. In order to get a response (whatever that manifests itself as), you must have 25,000 signatures (this year, it was amended to 100,000 signatures — here is a recent petition to have that rule rolled back to 25,000 again  — here, too). Here are some petitions that have gone over that limit:

… some on worthwhile issues (in my opinion):

• Support mandatory labelling of GMOs (over 65,000 signatures)
• Free access to scientific journals if the research is taxpayer-funded (58,887 signatures)
• Change all US measurements to metric (33,537 signatures in 1 month)
• Amend the constitution to get big money out of politics (23,556 after 2 weeks)
• Don’t veto Palestine’s application for membership in the UN (11,000 signatures since Sept/12 — pretty sad, actually)

… and here are some “interesting” ones:

• anything to do with actions against the Westboro Baptist Church (usually over 60,000 signatures)
• Anything to do with actions against Dianne Feinstein (normally over 25,000)
• Endorse the NRA’s National School Shield Program (36,827 signatures in 1 month)
• Allow Texas to secede from the Union (100,000 in 1 week last November)
• recount the election (69,006 signatures so far)
• don’t regualte premium cigars (36,270 signatures)
• mint a trillion dollar coin and place it in the Federal Reserve to avert a debt ceiling crisis (over 10,000 signatures in 2 weeks)

… and some ones that, I fear, may not make it past the 25,000 mark:

• Recognize International “Talk Like a Pirate Day”
• Get rid of Petitions.whitehouse.gov
• officially recognize the Sasquatch as an indigenous species
• ban hammers and baseball bats
• Save the “Lepty Lew”