Of all the things related to the show, I've always wanted to see more family of the Mane Six. As of Season 2, we have parents for Pinkie, Rarity, and Twilight, and siblings for Pinkie, Applejack, Rarity, and Twilight. Applejack herself has several cousins, and an Aunt and Uncle Orange. Sadly, we did not get anypony related to Rainbow Dash nor Fluttershy.
One of my hopes for Season 3 is that we at least see one relative of RD and/or Fluttershy.
What relatives do you want to see for the Mane Six? Personally, I want to at least see parents for Applejack, RD, and Fluttershy. Maybe we can have a brother for RD or FS?