Yesterday, SEGA announced downloadable content available exclusively to those who pre-order Sonic Boom: Rise of Lyric from Amazon. This DLC is a set of "luminous costumes" for Sonic, Tails, Amy and Knuckles. This offer is available to US residents only.
A first pre-order bonus had been revealed for both Rise of Lyric and Shattered Crystal two weeks ago: a Sonic action figure. This offer was available to US residents who pre-ordered from Gamestop, and Canadian residents who pre-ordered from EB Games.
You can preorder Sonic Boom: Rise of Lyric at Amazon or Gamestop, and Sonic Boom: Shattered Crystal at Amazon or Gamestop.