What is as amazing as the stamps is how they are mounted. I like Jim's description on the Stamp Community list: "Never have I seen an album so encrusted with stamps like barnacles on a hull." While I have seen album pages completely covered in stamps, they have invariably been ones where the stamps bore no relationship to what was intended by the editor to reside on the page. You can check out the images on Kelleher's website for a fraction of what was in the albums.
Here's the description from Kelleher's auction catalog (I corrected a few typos):
"Worldwide, Absolutely Extraordinary 3 Volume International Collection, 1840-1940. Forget what you have ever thought about International collections, as this magnificent, old-time collection is absolutely astounding in its breath of coverage. If there was no space allotted the owner just went ahead and created one. Duplicates or parallel mint and used coverage? Definitely not a problem, as the owner simply overlapped premium stamps one over another, often with a better mint example buried beneath. To list the endless quantities of premium individual stamps would be fruitless, though we will provide scans on the internet to give an overall flavor of the lot...About the only slight negative we can associate with this valuable lot is the time necessary to properly evaluate it. Turn each page and add it up; we've handled scores of International collections, but few like this one! Estimate $10,000 - 15,000."
While I would never mount a collection this way, you've got to admit that is unique.