This is only a small fraction of the scandals on the list! As always with Wikipedia, consider the source.
  1. Grangegate
    A political scandal involving former New South Wales' Premier Barry O'Farrell and a $3,000 bottle of Penfolds Grange.
  2. Donglegate
    A series of events following a double entendre on the word "dongle" overheard at a programmers convention March 17, 2013, which led to two people being fired and a DDoS attack.
  3. Bumpgate
    A controversial fist bump from NFL officials after a running touchdown against the Buffalo Bills by CJ Anderson of the Denver Broncosled some fans and players to believe a conspiracy existed against the team.
  4. Watergate
    The original "gate" scandal got its name from the Watergate Hotel, where two politically motivated burglaries took place in 1972. The Watergate scandal ultimately led to the resignation of U.S. President Richard Nixon on August 9, 1974. (Really the only "gate" that makes sense).
  5. Pastagate
    Montreal controversy, in which an Italian restaurant was investigated by the Quebec government for using words that do not comply with their language laws, such as "bottiglia," "calamari" and "pasta."
  6. Bottlegate
    Rowdy fans of the Cleveland Browns threw plastic bottles and other debris on the field after a controversially overturned call in the final minute of the game led to the Browns losing the game 15–10 to the Jacksonville Jaguars.
  7. Tunagate
    Canada political scandal involving large quantities of possibly spoiled tuna that were sold to the public.
  8. Waterkantgate
    Germany's answer to Watergate. A major political scandal involving espionage, tax fraud, and the mysterious death of politician Uwe Barschel, which is still unsolved.
  9. Nipplegate
    (Also known as Boobgate). Scandal that followed Justin Timberlake revealing Janet Jackson's breast during the halftime show of Super Bowl XXXVIII.
  10. Irisgate
    UK political scandal involving an affair by Iris Robinson MP MLA, wife of Northern Ireland's First Minister Peter Robinson.
  11. Moggigate
    Italian football scandal. Clubs of Italian Serie A were involved in a referee appointment scandal. Named after Juventus general managerLuciano Moggi.
  12. Squidgygate (also known as Dianagate)
    Tape of a telephone conversation between Diana, Princess of Wales and a male friend.
  13. Rathergate
    The scandal over a forged memo about George W. Bush's military record that ultimately led to the resignation of Dan Rather as anchor of CBS Evening News.
  14. Staingate
    Anger over reports that the anti-reflective coating appears to be wearing off several MacBook Pros, including mid-2012 to mid-2014 models sold between June 2012 and present.
  15. Toallagate
    Scandal in Mexico due to the high cost of bathroom towels (around US$400 apiece) bought for the official residence of the Mexican president.
  16. Strippergate
    The name of two separate government scandals and criminal investigations on the West Coast (Seattle and San Francisco) both involving strip clubs and organized crime.
  17. Fajitagate
    In November 2002, three off-duty San Francisco police officers allegedly assaulted two civilians over a bag of steak fajitas(which were mistaken as drugs), leading to the retirement of the chief of police and the firing of his successor.
  18. Corngate
    (Goes great with Fajitagate). A political scandal in New Zealand in 2002, which involved the suspected release of genetically modified corn seed in 2000.
  19. iPhone Antennagate
    Suggested by @ChrisK