Firefox 3.6 supports multiple file input. This new capability allows you to get several files as input at once, using standard technologies. This is a big improvement, since you used to be constrained to one file at a time, or needed to use a third party (proprietary) application. This will be particularly useful, for example, for photo uploads.

From multiple file input in Firefox 3.6. The post contains code examples and a link to a demo. You’ll need the beta version of Firefox 3.6 to take advantage.

Also see: Proposed File API specification