The Sakai course management system handles files, resources, and links really well, but the system does not support tagging. So, if you do want to sort or sift your files on numerous axes, you have to use a tool outside the system. Fortunately, assets in Sakai have specific, permanent URLs so you can use a social bookmarking service like Delicious.com to tag content.

Start by capturing the asset URL (right click, copy address) and post this new item with course-specific tags to Delicious (or similar system). Then, you can either link out to that bookmark list or use Sakai's RSS aggregators to feed specific lists of bookmarks into your Sakai site.