In the last few years PDF formatted files have been assuming a more significant role in online genealogy publishing.
The RootsMagic genealogy program can output PDF files. The Ancestral Quest program can produce very nice "linked" PDF reports from GEDCOM files. Other reports from genealogy programs can be converted to PDF using free or shareware programs.
The use of PDF insures that the recipient of the file can read and print the report with the free Adobe Acrobat Reader on their own computer.
There's a PDF page link on the homepage of my genealogy website. From the PDF page you can access several reports that I have made available to anyone who visits.
If you are interested in learning more here are links to some useful websites.