Bukkit

Here is a list of some nice WorldGuard Custom Flags plugins:

• WG Block Restricter - Black- and whitelist blocks in specific regions.
• WG Chat Flags - Modify the chat for players in a specific region.
• WG Chunk Flag - Disable unloading of specific regions.
• WG Command Flags - Block commands in specific regions.
• WG Drop Flags - Automatically despawn dropped items and deny picking up items in specific regions.
• WG EnderPearl Flag - Block enderpearls in specific regions.
• WG Explosion Flags - Block certain kinds of explosions in specific regions.
• WG Fly Flag - Allows players to fly in specific regions.
• WG Instabreak Flag - Allow everybody who can build to instabreak all blocks in specific regions.
• WG Keep Inventory Flags - Allows players to keep there inventory and/or level in specific regions.
• WG MobDamage Flags - Block any damage to specific mobs in a WorldGuard region
• WG PlayerDamage Flags - Block specific damage types on players in specific regions.
• WG Region Commands - execute a command when a player enters/leaves a region.
• WG Region Effects - Add constant potion effects to players in specific regions.
• WG Region Permissions (planned)
• WG Sign Flags - Block signs in specific regions.
• WG Spawn Point Flag - Set a respawn location for players who die inside a specific region.
• WG Texture Pack Flag - Set texture packs for specific regions.
• WG Time Flags - Modify the time in single regions.
• WG TreeFarm Flag - Plant and protect saplings where a tree gets destroyed and block block placement inside of these regions even if player is op/can build.

Third party plugins:

• OreRegenerator - Regenerate ores (or any other kind of block) after some time.