Only files under 25 MB can be previewed with the Google Drive viewer.
Google Drive viewer helps you preview over 16 different file types, listed below:
- Image files (.JPEG, .PNG, .GIF, .TIFF, .BMP)
 - Video files (WebM, .MPEG4, .3GPP, .MOV, .AVI, .MPEGPS, .WMV, .FLV)
 - Text files (.TXT)
 - Markup/Code (.CSS, .HTML, .PHP, .C, .CPP, .H, .HPP, .JS)
 - Microsoft Word (.DOC and .DOCX)
 - Microsoft Excel (.XLS and .XLSX)
 - Microsoft PowerPoint (.PPT and .PPTX)
 - Adobe Portable Document Format (.PDF)
 - Apple Pages (.PAGES)
 - Adobe Illustrator (.AI)
 - Adobe Photoshop (.PSD)
 - Tagged Image File Format (.TIFF)
 - Autodesk AutoCad (.DXF)
 - Scalable Vector Graphics (.SVG)
 - PostScript (.EPS, .PS)
 - TrueType (.TTF)
 - XML Paper Specification (.XPS)
 - Archive file types (.ZIP and .RAR)
 
https://docs.google.com/a/[DOMINIO]/viewer?url=[FILE_URL]
https://docs.google.com/a/[DOMINIO]/viewer?url=[FILE_URL]
##Office Web Apps Viewer ('.ppt' '.pptx' '.doc', '.docx', '.xls', '.xlsx')
http://view.officeapps.live.com/op/view.aspx?src=[OFFICE_FILE_URL]
<iframe src='https://view.officeapps.live.com/op/embed.aspx?src=[OFFICE_FILE_URL]' width='px' height='px' frameborder='0'>
</iframe>
Info: http://www.labnol.org/internet/google-docs-viewer-alternative/
Is there any way to increase limit of 25 MB ?