What a time to be watching your favorite Superheroes on TV! Arrow and Agents of Shield have both been getting good reviews, and then we get not one, but two trailers for DC themed TV shows. Gotham, a pre Batman show centered on a young Jim Gordon; and The Flash, a show about... well... the Flash.
It looks like DC has finally learned its lesson from Marvel, and will be connecting its shows as well. In the five minute long The Flash trailer, we see Barry discussing crime fighting with none other than Oliver Queen from Arrow.
My suggestion is to start catching up on Arrow now, so you can pick up on what are sure to be many Easter eggs between shows. I'd like to hope that Gotham is also connected, but the shows are on different networks, so that may not be the case. Arrow - The complete first season 
For those of you who want even more comic goodness, check out some of these stories from your branch library.
Youtube videos of the trailers can be found here: