If someone sends you a read-only version of a Google document or spreadsheet and you want to download it as a PDF and link to that PDF from your site, there's an easy way to do it.

For spreadsheets

A published spreadsheet has an address that looks like this: http://spreadsheets.google.com/pub?key=[ID]. To get the address for a different format, you need to append &output=, followed by the extension of the format. For example, http://spreadsheets.google.com/pub?key=[ID]&output=xls for Microsoft Excel spreadsheets. Other valid output formats: pdf, ods (for OpenOffice spreadsheets), csv, txt.

For documents

Published documents have a similar URL: http://docs.google.com/View?docid=[ID]. To obtain the address for another format, you'll have to use the docid parameter:
http://docs.google.com/MiscCommands?command=saveasdoc&
exportformat=[FORMAT]&docID=[ID], where [FORMAT] can have one of these values: pdf, doc, oo (for OpenOffice documents), rtf, txt.

Another way to download the files is to go to Google Docs homepage and open the files from there, but, at least in the case of spreadsheets, the method described above lets you actually link to the file in a different format and people that click on the link don't need to have a Google account. For documents, a visitor of your site has to log in with his/her Google account before clicking on the link.

{ From an idea of DPic. } </img> </img> </img> </img>