Eric Mann

WP Publication Archive adds a custom content type for storing, tagging, and categorizing downloadable content external to standard WordPress posts and pages. You can add downloadable PDF files, Word documents, and PowerPoint presentations. These files will be stored in the standard WordPress uploads directory but will be managed separately through a custom post type interface in the WordPress admin area.
<h3>Licenses</h3>
WP Publication Archive is licensed under the GNU General Public License, version 2.
This system was based on the original wp-publications-archive plug-in published by Luis Lino and Siemens Networks, S.A. at http://code.google.com/p/wp-publications-archive/.
The filing cabinet menu icon was created by Glyphish (http://glyphish.com) and is distributed under a Creative Commons Attribution license.
Filetype icons come from the Crystal Project (http://www.everaldo.com/crystal/) released under the LGPL (http://www.everaldo.com/crystal/?action=license).

WP Publication Archive

Allows users to upload, manage, search, and download publications, documents, and similar content (PDF, Power-Point, etc.).

danlester

Google Doc Embedder lets you embed several types of files into your WordPress pages using the free Google Docs Viewer – allowing inline viewing (and optional downloading) of a wide range of popular file types, with no Flash or PDF browser plug-ins required.
<blockquote>
NOTE: Recent changes by Google to their viewer mean that some other plugins may be more suitable:
<ul>
<li>If you are able to store your files in Google Drive, try the <a href="http://wp-glogin.com/wpgoogledoctodrive" rel="nofollow ugc">Google Drive Embedder plugin</a>. This will be faster to display, and more reliable.</li>
<li>To make it difficult for users to download the full PDF (the old ‘enhanced mode’), please find out more about <a href="http://wp-pdf.com/secure/?utm_source=GDE%20Readme&utm_medium=wordpressorg&utm_campaign=Freemium" rel="nofollow ugc">our new plugin – PDF Embedder Secure</a>.</li>
<li>Mobile-friendly functionality for viewing PDFs is available in <a href="http://wp-pdf.com/premium/?utm_source=GDE%20Readme%20Premium&utm_medium=wordpressorg&utm_campaign=Freemium" rel="nofollow ugc">PDF Embedder Premium</a>.</li>
</ul>
If this plugin works as you require then feel free to continue to use it, but please do not expect support beyond urgent security fixes. It is not guaranteed that Google will continue to offer or support their Document Viewer.
</blockquote>
<h4>More about Google Doc Embedder</h4>
Similar to services like Scribd, Google Doc Embedder will allow you to embed these files directly into your page or post, not requiring 
the user to have Microsoft Word, Adobe Reader, PowerPoint, or other software installed to view the contents. Unlike Scribd, the files do 
not need to be uploaded to any service first – including Google Docs – but can exist anywhere publicly accessible on your site or the 
internet.
Supported file formats include:
<ul>
<li>Adobe Acrobat (PDF)</li>
<li>Microsoft Word (DOC/DOCX*)</li>
<li>Microsoft PowerPoint (PPT/PPTX*)</li>
<li>Microsoft Excel (XLS/XLSX*)</li>
<li>TIFF Images (TIF, TIFF)</li>
<li>Apple Pages (PAGES)</li>
<li>Adobe Illustrator (AI)</li>
<li>Adobe Photoshop (PSD)</li>
<li>Autodesk AutoCad (DXF)</li>
<li>Scalable Vector Graphics (SVG)</li>
<li>PostScript (EPS/PS)</li>
<li>OpenType/TrueType Fonts (OTF, TTF)</li>
<li>XML Paper Specification (XPS)</li>
<li>Archive Files (ZIP/RAR)</li>
</ul>
Office XML (2007+) file formats are sometimes problematic with Google Viewer. Please test your documents, and when possible I recommend 
you use the Office 2003 equivalent formats instead.
Note: Use of this plug-in implies your agreement with Google’s published <a href="http://docs.google.com/viewer/TOS?hl=en" title="Terms of Service" rel="nofollow ugc">Terms of Service</a>.
Translations:
<ul>
<li>English (en_US), built-in</li>
<li>Czech (cs_CZ) by Jirka, thanks!</li>
<li>Dutch (nl_NL) by Niko Strijbol, thanks!</li>
<li>French (fr_FR) by <a href="https://profiles.wordpress.org/erwanlescop" title="Erwan" rel="nofollow ugc">Erwan</a>, thanks!</li>
<li>Hungarian (hu_HU) by <a href="https://profiles.wordpress.org/szemcse" title="szemcse" rel="nofollow ugc">szemcse</a>, thanks!</li>
<li>Italian (it_IT) by <a href="https://plus.google.com/+MarcoMardegan" title="Marco" rel="nofollow ugc">Marco</a>, thanks!</li>
<li>Russian (ru_RU) by Józek, thanks!</li>
<li>Spanish (es_ES) by <a href="http://elarequi.com/propuestastic/" title="elarequi" rel="nofollow ugc">elarequi</a>, thanks!</li>
<li>Turkish (tr_TR) by <a href="https://profiles.wordpress.org/lettoblog" title="LettoBlog" rel="nofollow ugc">LettoBlog</a>, thanks!</li>
<li>Ukrainian (uk) by Józek, thanks!</li>
</ul>
Many thanks to the original author of the plugin, Kevin Davis.

Google Doc Embedder

Lets you embed PDF, MS Office, and many other file types in a web page using the free Google Docs Viewer (no Flash or PDF browser plug-ins required).

WP Publication Archive vs Google Doc Embedder