Next question: *tagged* note taker?

I want to thank everyone for all the suggestions in
this thread regarding tabbed text editors.
Unfortunately, nothing is exactly *IT* – but I've been using
TextWrangler over the weekend and I think it will end up in my arsenal anyway, even though it's not technically everything I'm looking for. The drop-down menu for accessing files instead of tabs is a close second. Plus, you can't beat free. :)

But I have yet another question for your collective knowledge wisdom. The fatal flaw with keeping text files of notes is that, once you close them, you can't search them. I know that
Spotlight will address this, but gol-darnit, I hate waiting. On the other hand, the fatal flaw with knowledge collectors like DevonThink and StickyBrain is that they keep your files in proprietary databases that you have to remember to backup and/or export periodically. Try as I might, I
can never seem to 'remember' to do these sorts of periodic actions.

So my new question is two-fold: are there any note collector/research-oriented apps that collect and store files in standard formats, yet keep them always searchable? Part two is: are there any note-taking apps that allow you to organize your notes by tagging them instead of by placing them in hierarchies? By tagging I mean an easy way to attach any number of non-hierarchical attributes to a note, the way that Flickr and
del.icio.us allow you to do. If something like this exists for OS X, I would probably switch to it in a heartbeat.

Again, thanks in advance for any suggestions!