Playerlist
Fleckenstein

Show a list of all online players (similar to minecrafts tab-list) when a player is sneaking.

Mineclone2 Spyglass
NO11

This adds a spyglass, which is an item that can be used for zooming in on specific locations.

Witt 2(What Is This Thing)
pevernow

Witt can display the name, source module and details of the target that any player points to.

Mudsling
Avicennia_g

Inverted-direction player slingshot

HUD bars
Wuzzy

Replaces the default health and breath symbols by horizontal colored bars with text showing the number. Extensible.

Oretracker
ApolloX

For tracking what ores are around the player.

Complete and Total Lua-Only Inventory Rewrite
Noodlemire

Creates a completely custom inventory system, which doesn't rely at all on any of the usual UserData objects.

HUD Compass
kestral

Optionally place a HUD compass and 24-hour clock on the screen.