• View PDF, PPt and Tiff online with Google Docs, even you do not have a Google Account or you do not want to login it. and you can embed the online documents into your own web pages.
• Google Docs add OCR support to PDF and Images, so you can OCR your scanned PDF, Fax, Images without any fee.
• Built-in PDF Reader for Google Chrome, view PDF just like view html. Chromium’s blog announced that the latest Google Chrome dev build for Windows and Mac includes a plug-in for viewing PDF files. The plug-in can be enabled by going to chrome://plugins/ and clicking on “Enable” for the “Chrome PDF Viewer” plug-in.
  When you click on a link to a PDF file, Chrome no longer opens the file using the Adobe Reader plug-in. Instead, Google Chrome uses a basic PDF viewer that lacks many useful features like pagination and bookmarks.

Google Docs Viewer is an undocumented feature of Google docs, with it, you can quickly view documents online without leaving your browser, of course, the documents should be online. PDF documents, PowerPoint presentations, and TIFF files are supported.
you can directly put the url of online document to the end of “http://docs.google.com/gview?url=”, for example, http://docs.google.com/gview?url=http://soft.rubypdf.com/itext/sample-ch01_Lowagie.pdf
and you can easily embed the online document into your webpage
<iframe src=”http://docs.google.com/gview?url=http://soft.rubypdf.com/itext/sample-ch01_Lowagie.pdf&embedded=true” style=”width:600px; height:500px;” frameborder=”0″>

btw, Google Docs add OCR support to PDF and Images, but if you want to search scanned PDF or Tiff, you still have to upload them to your owner Google account.

From PC Pro, I got Google introduces Presentation PDF support,

Google has added PDF support to the presentations component of Google Docs.
Presentation can now export slides in the PDF format, enabling presentations to be saved offline. There’s also a set of PDF-based printing options that enable up to 12 slides to be printed on single sheet.

So I did a try, it also supports Chinese, but I found it try to use Japanese font by default, so some Chinese characters will be lost, maybe they do not exist in Kanji(Japanese character) database.