What's the timer on the tower in Lynchwood used for?
There is a digital timer by the tower to the train station entrance. Is there any purpose to it? What sort of time does it keep?
It's not a timer, but a clock (as you would expect to find at a train station). The time does correctly correspond to the night/day cycle, so it can be used to figure out how long you have before night/day.
Well That is a Clock and it could be used for finishing the challenge where you have to kill a bruiser on 5 O clock train.
Its there to let you know when 5'O clock train is coming. :D