It is an ebook format, it's just not one which meets the OP's current needs or equipment.
I read 8.5" x 11" .pdfs on a Compaq laptop quite frequently (just set them to be rotated 90 degrees and hold the laptop like a book), and smaller sized .pdfs work fine on either my Fujitsu Stylstic or my Sony PRS-505 --- I'm reading Geronimo's autobiography (made available as a very nice .pdf by Jose Menendez / Elegant Ebooks ---
http://www.ibiblio.org/ebooks/ ) to my kids on my Sony (we've been reading biographies of American presidents other notables and had just finished Theodore Roosevelt, since TR authorized the writing of Geronimo's autobiography it was a natural segue).
William
W