Eric's heavily into keywording, but I'm just...not. I've never really known why I couldn't get into it, but last night I realised: Aperture's beautiful hierarchical keywording system paralyses some part of my brain. I can't bring myself to add copious tags, Flickr-style. I have to worry about where they fit in the hierarchy, whether the "Greenock" tag really belongs in the /Travel/UK/Scotland hierarchy or somewhere else or, indeed, whether "UK/Scotland" should be under /Travel and not, say, /Home or some such.
See? I can't live with disorder and I can't cope with the demands of maintaining order. Actually, that pretty much sums up my life.
Update: A couple of commenters have mentioned how frustrating it is that FlickrExport uses the entire keyword hierarchy path to fill out a photo's Flickr keywords. That's just the default, and there's a preference: Change the "Fill Flickr Tags From:" preference from "Full Aperture Keyword Hierarchy" to "Image Tags Only" and only the leaf tags in the tree will be used.