windharp - 5:03 am on Aug 29, 2007 (gmt 0)

"optimum" for whom?

--> For SEO purposes?
I don't know and honestly I don't care either.

--> For the user?
That is really difficult to say. While the user expects categories that are "complete", large categories scare him away as well. So you might try to go with only a maximum number of handpicked entries. But (especially if your topics are even slightly commercial) you will soon have topics where you have no clue which <n> to select. In the ODP, our rule of thumb is that categories with more than 20 entries could do with subcategories. Due to the nature of some topics, dividing is not always an option, though. If you want to stay complete, you will naturally get to the point where you can't subdivide by topic, you would have to start something like an alphabar dividing a topic by alphabet (which is extremely userunfriendly).

If someone knows any (online available) research papers aboutthis topic, I am sure many readers would be interested.