Bukkit

SmoothPlot - simple but powerful plots managment system - no pre-defined regions required - WorldGuard based

Create custom shaped regions using WorldGuards polygonal regions, all with a simple command

For servers that don't use plugins for PvP arenas and use WorldGuard for their arenas.

A plugin that makes a certain WorldGuard region rain.

Plugin to block items and protect blocks, with WorldGuard support

adds events for entering and leaving WorldGuard regions to Bukkit

WorldGuard Region Effects lets you give WorldGuard regions effects.

black-/or whitelist blocks in WorldGuard regions

WorldGuard Custom Flags

Adds flags to WorldGuard that allow you to protect mobs from damage.

block certain explosion types in WorldGuard regions

Allows you to enable fly mode in specific WorldGuard regions.

Adds flags to WorldGuard to toggle if a player keeps his inventory/level if he dies in a certain region.

Allows you to automatically execute commands if a player enters/leaves a WorldGuard region.

Adds flags to WorldGuard that allow you to automatically remove items dropped in specific regions after some time.

Allows you to setup per-region texturepacks on your server.

Allows you to set different times for different WorldGuard Regions

Adds flags to WorldGuard to modify the chat for players that are in a specific region

Keep specific WorldGuard regions loaded

Set a respawn location for any WorldGuard region

Hides players in the Tablist which are outside of a specific WorldGuard region.

Adds some flags for worldguard such as gravity.

AdvancedRegionMarket (ARM) allows you to sell, rent and manage WorldGuard regions

Users will gain a certain permission node when entering a WorldGuard region for the first time.

Add a region flag to WorldGuard to stop players from rotating items inside of item frames.