Bukkit

Inexpensively protects your ores from cheaters.

a feature-rich world size limiting plugin, which can also generate or trim a world to your border

The best-rated server backup plugin with cloud upload! Works with Google Drive/OneDrive/Dropbox/FTP/WebDav with super simple setup.

Protect and lock Chests, Furnaces, etc. with a easy to use GUI.

CrazyLogin

Residence

Guilds, war, land claiming, and user-controlled antigrief

Terrain creation ingame using 3D brushes

PlotSquared

Advanced /vanish plugin which makes other players think that you're not on the server

Repairs Creeper and TNT damage after a while, and much more!

Player property protection using special block placement.

Seeing light in your darkest hour

Nerf those creepers

The premier long-range map editing tool for Minecraft SMP.

EntityManager

Stables provide steed protection, and other horse related things.

Detect and Fight the exploitation of various Flaws/Bugs in Minecraft

Advanced secure for region from WorldGuard

CommandRank