[YepYep]

I use Adobe Acrobat 9 Pro to open up pdf's with a lot of whitespace and select the crop tool (works only in non-secured pdf's). There is a button to apply this crop-selection you have made to all pages at the same time (but it is better to do even and uneven pages separately). I crop as close as possible to the text block. Forget about any headings or pagenumbers, just crop the text block because your e-reader will show the page number anyway.

If in portrait mode this still makes for undesirably small page size, then turn on landscape mode. This works great for me.

Also note that you will probably not want to convert your pdf into a textfile (either by e-mailing Adobe or by clicking on Medium/Large on your Sony e-reader). Changing your pdf into a textfile will mess up the lay-out, pictures and will forget about any special characters (and formula's etc.). This whole exercise is to keep the article/book you're reading in the original state but with as little white space as possible.

Note to students, check with your university if they offer a free a copy of Adobe Master Suite (or maybe not free but for a small fee), mine did.