I noticed that both google doc viewer and Zoho cannot handle *.pps file correctly, at least for some pps fle.

Is there a plugin that handles MS Office files well? For example, doc/docx, ppt files etc?

Thanks for your help

All the plugins we know of are listed here http://www.zenphoto.org/news/category/extensions

But I suggest you use a "compatible" format for your documents. Probably those sites just do not handle the most recent document versions.