It's no stretch to assume that ZDNet readers have at least one free app on their hard drive that they can't live without. And as we head toward a Netbook-flavored world, those favorite apps have to be lightweight, too (or maybe even portable).
We're open to any app category, by the way: communication apps, word processing apps, photo apps, media managers, browsers, security apps, system managers, you name it. If you have apps that are a "must-install" on a fresh install of Windows, let's hear those, too.
Leave your suggestions in the comments, and I'll produce a follow-up post tallying the results.