How to build elevators in single player mode?
Solution 1:
Since water-related elevators no longer work after 1.6, the best way to do this is to use a minecart elevator:
Minecarts teleport you into them as long as you're relatively close when click on them, so you can use minecarts stacked one on top of another to click your way up to freedom.
Solution 2:
Or you could make a piston elevator. I just finished mine, and it's still small (7 pistons), but it works.
Faster version (sea level to height limit in 12.8 seconds):
Solution 3:
A non-mod, and only slightly hacky way of travelling up/down fast is with boat/minecart elevators, of which there are plenty of video tutorials.
Mod-wise the only thing I can find is Ethereal's Elevator Mod, but it hasn't been updated for a while.