I was watching one of those Enterprise episodes from the fourth season with Brent Spiner and in that one episode, there were references to the Original Series, a Movie, the Next Generation and Deep Space Nine!
The Botany Bay and Kahn Singh from "Sapce Seed"
The Briar Patch from ST:Insurrection also called Klach D'Kel Brakt, mentioned in Deep Space Nine.
Soong made hints toward pursuing cybernetics at the end of the episode. Clearly a reference of Data from The Next Generation.
I thought it was neat that they'd make so many references of already established stuff in Trekdom.