Virtual folders?

there is certainly no easy way to do that and I don't know if it's possible at all. AFAIK, the only true virtual folder in OS X is Trash. you do need to use aliases or hard or soft links. you can create a bunch o aliases a once. select the files and commandoptiondrag them to the folder where you want to create aliases.

You could make them fit Smart Folder criteria, for example using Spotlight Comments. There are several tagging applications available to facilitate this approach. (One that I know about, but haven't gotten around to trying, is called Leap. See versiontracker.com or macupdates.com)

I thought of another approach: use a Burn Folder (Finder: File > New Burn Folder). A Burn Folder contains aliases of files that are intended to be burned to a CD or DVD. But you don't actually have to burn a disc. Any file you drag into a Burn Folder is added as an alias. The file remains in its original location.