MIT Open Courseware is a FREE and exceptionally well produced set of educational topics, lectures, lecture notes and handouts. The notes and handouts are in Adobe PDF format only. But if you want to read them on your Amazon Kindle Reader, you will need to convert them. Fortunately, there is a process for doing this that is fairly simple, and totally free. Be advised however, that converting PDF files to e-book formats is not a flawless effort. Formatting will be changed, but in general, the textual content remains intact.
1. Browse the MIT OCW library and find a topic (e.g. "Modal Logic", http://ocw.mit.edu/courses/linguistics-and-philosophy/24-244-modal-logic-fall-2009/lecture-notes/)
2. Right-click on the "PDF" link for one of the Lecture Notes, copy the Link Address
3. Go to http://www.2epub.com
4. Click the "BROWSE" button, and paste the PDF hyperlink into the filename box, click Open
5. Click the "Upload Files" link
6. Select the option to convert to .MOBI
7. Download the results of the conversion
8. Open in Kindle Reader app or copy to your Kindle Reader device
You can also convert to EPUB format for Sony Reader and the B&N Nook Reader.