I recently bought a Kindle and have started loading it with techy books/papers/etc. that I can find for free. I am using the free calibre (http://calibre-ebook.com) software to do the conversion since pretty much everything I find is in PDF format.

It works OK for 1-column PDFs, but for 2-column the conversion does not work at all. I can read PDFs on my Kindle, but it is not as nice as reading an actual ebook.

I found one way to convert them in case anyone else is interested:

1) Upload the PDF to Google Docs 2) Choose to "Make a Google Docs Copy" which will convert it into the Google Docs document format that you can edit 3) Tweak as needed 4) Download as HTML 5) Load into Calibre and convert to your book type (mobi, epub, etc)

This will only convert the first 10 pages though, so you might need to split the original PDF (with a site like http://foxyutils.com/splitpdf ). However, if it gets too long this method will get pretty tedious.

If you have any questions or thoughts, let me know.