"The customize button should also give you the option of changing the number of items per page. Right at the bottom of the options when you're in that screen. Goes up to 200 items to display."
I finally found the thing you're talking about, but it only allows you to go up to 25. Besides, I think it's only talking about the summary, not about the actual items for auction (etc) in My eBay. 😞
NEGATIVE FEEDBACK FOR YOU, EBAY! 😄
Another thing I noticed today is that in "Customize My Summary" you can't choose to not view eBay announcements or Buying/Selling reminders. Those are the ones I'd prefer not to view, and yet those are the ones that are mandatory. So much for customization eh?