Toolfarm's Plug-in Finder

Weather

Rain, snow, sleet, tornadoes, skies, wind, etc.

The Foundry Tinderbox 1 - Includes sky generators, light rays, hand-drawn etch effects, heat haze, water caustics, matte dilation tools, and the fastest software Gaussian blur for After Effects.
The Foundry Tinderbox 3 - Includes BadTV, OldFilm, MeltTime, Lightning, Turner, Sparks, and Condensation, as well as various blurs and some handy compositing tools.

Boris FX, Inc. Continuum Basics - 30 filters from the award-winning Boris Boris FX, Inc. Continuum Complete plug-in suite.
Boris FX, Inc. Boris FX - More than 60 filters include motion tracking and image stabilization, as well as self-animating natural effects that easily interact with timeline video.
Boris FX, Inc. Final Effects Complete - Otherwise known as simply "FEC" and recently acquired by Boris from Optibase via Media100, originally developed by Cycore, Final Effects Complete is a collection of over 100 plug-ins.
Boris FX, Inc. Graffiti - Provides integrated broadcast-quality 2D and 3D titling features.
Boris FX, Inc. RED - The only integrated 3D compositing, titling, and effects application to over twenty nonlinear editing applications.

Digital Element Aurora Sky - Create skies and clouds in your AE or FCP composition, but without a 3D program.