Crying Obsidian

In the original beta, beds let players skip the night and set a respawn point with three wool and three planks. Crying Obsidian replaces that convenience with a harder route: a respawn point is set by right-clicking a Crying Obsidian block while holding a Diamond, and the diamond is absorbed in the process. Once a point is set, the block cannot be moved without mining it, and mining it drops a single block that has to be placed again.

The mod adds the Ghast Tear, which a Ghast drops with a one in three chance when killed, and uses it as a required ingredient in the Crying Obsidian recipe. Players must gather Nether material before they can build the block at all, so the challenge reaches into the Nether. The mod is client and server, so both the server and every player need it, and it requires ModLoader. It is published for b1.2_02 only, under the Creative Commons Attribution Non Commercial No Derivatives 4.0 license, and is not open source.