Ever spend hours grinding a way just to dig out a slime spawning chunk, when you could have been exploring new parts of your world?

This very simple mod tells you the coordinates of the nearest slime or magma cube, as far away as you can load chunks. Large slimes are pretty rare, but will often reveal the location of hidden caverns.
Press f7 (configurable) to toggle it on/off.

Slime farm owners will also benefit, in that they don't have to keep backtracking to check for slimes spawns.

NOTE 1: Due to the low spawn rate (1/10th of other mobs, in 1/10th of the chunks at the lowest spawn rate) It may take time for slimes to spawn. Nonetheless you're guaranteed to have more than enough slime balls, with a bit of travel and exploration over time.

NOTE 2: it works on all servers as well.
Just make sure that the admins are okay with you using it.