Crocodoc is a great, free tool that I have used often. It is an online service that allows you to upload and markup documents, including PDF files. You can not actually edit the PDF file, but can add text, highlight, draw, and even strikeout text. When you strikeout text, it opens a new text box above the strikeout for you to edit. You can even collaboratively work on documents with other people.
The personal sharing and markup service is now at http://personal.crocodoc.com/
Today, Crocodoc announced that it has new technology and features, adding HTML5 document embedding for PDF files and Microsoft Office files to web products. Crocodoc originally used Flash on it's site and then last year launched it using HTML5 for mobile work.
The new features announced today will allow users to use Crocodc to embed documents into any mobile app or web app. Dropbox, LinkedIn, Yammer, and SAP are using this technology. This is what powers Dropbox's ability to allow you to view documents in your web browser and mobile device without having to download the file.
So, what does this mean for education? It means we can see more web based and mobile apps that can do more with documents. This can help educators share and use documents on mobile devices themselves and with their colleagues and students. It also means that Crocodoc is doing well and should be around for a while, letting us continue to use their excellent site to markup, share, collaborate, and annotate files.
Check out Crocodoc. http://personal.crocodoc.com/
Crocodoc - markup PDF files for free
Lots of PDF resources - print, markup, convert and more