Project management like "Post Haste" from Digital Rebellion
Project management like "Post Haste" from Digital Rebellion would be a hierarchy of folders setup up from your Preferences.
In the preferences the user could designate a set of folders within folders (up to two layers deep?). A main search may search all the media files within its subfolders (hence the restricted levels) but the 2nd level folders would only filter [ie - type "A" and shows only the files named "apple, aid, & agree" but type "AG" and it only shows "agree"] and make the lag at least a full second after tyoing stops to avoid annoyingly rapid reordering. This should make searching context sensitive and as memory-efficient as possible.