PDF4Kindle is a neat little free service that will convert PDFs into .mobi format for reading on Kindle devices. To use the service all that you need to do is upload a PDF and let PDF4Kindle do the rest. When the conversion is complete you can download the .mobi file. The converted file will let you resize text as you would with any other Kindle document.
Applications for Education
PDF4Kindle could be a helpful service for schools that are issuing Kindles to students. Rather than just distributing PDFs which may not have all of the functionality of .mobi files you can distribute functioning .mobi files to your students. Doing this could potentially expand the library of reading materials available to your students.
H/T to Life Hacker.