Sounds
AntumDeluge

A set of free sounds & API.

Epic
BuckarooBanzai

Enhanced Programmer for Ingame Control

City Block II
sorcerykid

Disables use of water and lava buckets within a designated area

Placeable Buckets for Catching Rainwater
Noodlemire

Allows empty buckets to be placed as nodes in order to collect rainwater.

Climate API
TestificateMods

A powerful engine for weather presets and visual effects. Requires a weather pack like Regional Weather.