Maybe I should start a different topic for this, but if the way tags work right now, they are barely more effective than subfolders.
They have a slight advantage in that .. well for example, I have Requests for Information, Draw Requests, and Submittals I keep track of for a construction project. I'm using tags of rfi, draw, and submittal to tags those documents or notes regarding those documents. (linking the notes to document is GREAT btw). I also use tags for the status; pending, approved, declined
Right now, if I look at notes with the status of pending I see all three items.. RFI, Submittals, Draws... what I would like to do is then click one of those tags, so I could see just the pending RFIs. (and this applies to any item, be it tasks, documents, notes, etc).
A good example of how this is done is JuxtaPhoto, which I use for a personal gallery - check out
http://photos.upmykilt.net/tags/blue%2Bridge - those are all my photos tagged with the tag "blue ridge". It tells me these photos also contain at least one of five other tags; lo-res, mountains, places, va, and mabry mill. If I click one of those, say mabry mill it shows me the photos that match both those tags, and so-on.
This is one of the most effective implementation of tags I've ever used... and if this could be added to OpenGoo I believe it would really make tags a viable alternative to folders for sorting documents and such.