We wrote an app to create invoices for my company as PDF for easy printing. Had a lot of good feedback from business associated so we released it as a full paid app (With free accounts) - <a href="http://www.rocketmailmerge.com" rel="nofollow">http://www.rocketmailmerge.com</a>
My personal website for a long time was just a full-page resume, with a link to a pdf version of it. I also post free textbooks for my classmates sometimes.