I was actually surprised when I first started Fairy Tail because of the small references it had from Rave Master. 

Ex: Plue (Mostly plue), Grey's necklace, Edolas Erza's weapon, the Jiggle Butt Bandits, and a giant robot golem Grif thing.

Sigh, it would be great if they went back to animating Rave Master once Fairy Tail. But saying that makes me feel bad because I don't want Fairy Tail to be over lol.