Also, with the addition of Ray Palmer, AKA the Atom, played by Brandon Routh, Oliver will have some competition (that's not evil) for his company, Felicity's attentions, and as a hero. Crossover episodes with The Flash were promised, as well as diving further into Ollie's time with Amanda Waller in Hong Kong where he meets the mysterious Katana.
Oh, and we didn't forget Thea and Malcolm - they were very sly about the direction of that storyline, but according to Willa Holland, "All I can say is that I've had to start hitting the gym a little bit. She's definitely made a big change. There's no more Vertigo, dancing on table tops Thea. The Thea that you saw in Seasons 1 and 2 is gone."
It looks like the new season is ramping up for even bigger things (Ra’s al Ghul!!), and the show and its stars are showing no signs of slowing down.