The 602 Club was a bar in Mill Valley on Earth in the 22nd century. Many of the pilots and engineers involved in the NX Project based at the Warp Five Complex frequented this establishment, including Jonathan Archer, A.G. Robinson, Charles Tucker III, and Malcolm Reed. The walls of the 602 Club were decorated with many astronautical illustrations, including a portrait of Zefram Cochrane's warp drive prototype Phoenix, a DY-100 class sleeper ship, and USS Enterprise (XCV 330). (ENT: "Shuttlepod One", "First Flight")
One of the waitresses at the 602 Club, Ruby, was known to have been romantically involved with two crewmen from Enterprise NX-01, Charles Tucker III and Malcolm Reed. Tucker went so far as to call her "the one." (ENT: "Shuttlepod One")
Charles Tucker promised to buy the NX-01 engineering staff, as well as Captain Archer and T'Pol, a round at the 602 Club for their excellent work during the Delphic Expanse mission. (ENT: "Countdown")
It is likely that the 602 Club was named for a bar  near the University of Wisconsin–Madison, Rick Berman's alma mater. Berman, along with Brannon Braga, wrote the Enterprise episode "Shuttlepod One", which marks the first mention of the 602 Club. Both are credited with creating the series as well.