Recommendations for Category Structure

Categorizing (also called doxonomy - I think) is different from keywording, and helps in casual visitors find interesting images on one's website or computer.

There are as many category trees as there are people, but I would like some of your suggestions anyway.

My dilemma is between very few top levels, e.g. Commercial, Personal, Portfolio
versius an extensive list, which makes the visitor go "Aha" quicker.

OK, let's hear from the masses...
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paul szilard
http://photos.remektek.com.au