I want to enter timestamped notes, and tag them with keywords. But unlike the tools I have found on the market, I want it to work like iPhoto, where I can use these keywords as a boolean selection but point and click, dynammically showing which items match the criteria selected.

In iPhoto, this is a tremendously powerful approach, allowing multiple classification categories of sub-classifiers to exist in one list, and pick the set that matches your data retrieval needs. None of the 2 dozen or more tools I have experimented with does this.

Supernotecard and Scrivener both are not designed for this, but come closest to actually providing this level of capabilities. Relationship from Jumsoft does a good job, but it is person/contact centric, which, for some uses, is ideal. Personally, I want more flexibility in my base dataset.