I got an email this morning offering the following...
Apparently a company who make BorisFX are giving away a free 'snow generating' filter for a number of popular editing and compositing apps. Here's part of what they said...
'BCC Snow is an auto-animated snow generator. The filter offers extensive options and allows you to create drifts or make flakes pile up along the edges of an alpha channel. For a limited time, download BCC Snow for FREE!
Adobe CS3 | Apple Final Cut Studio 2 | Autodesk Systems
This offer expires on March 1, 2008; you must install the filter before this date.'
The link for the Adobe CS3 filter is Boris Registration Form
You have to register some details with them.