You could go with classic pig names from television. There are Porky, Babe, Miss Piggy, Petunia, Piglet, Wilbur, Wagner, Gordy, Arnold Ziffle, or Porkchop.
Its nice to pick a band to name a litter after. I also personally like to name my litters after movie characters, hence the latest: Sweeney, Lovy, Toby, and Beadle. You might also choose rhyming names or Joe Bob, Jim Bob, Sue Bob, Lila Bob, Bob bob, and, of course, Bubba.
Choose names that are unique and that work well together. Pick a letter in the alphabet and use that letter to name all your pigs or choose rhyming names.
You could name the pigs after sounds that pigs make, like "Oink" and "Squeal. " Or you could name them after the Seven Dwarves or other storybook characters.