I have a wordpress site about 25 pages, is it possible to click and make a PDF from the whole site ?
You can write a program using http://code.google.com/p/dompdf/ make a button working off a click event. But i'm guessing you want to click a button already made some where to convert your pages to PDF's. In that case have you Googled
HTML to PDF I see a whole bunch of websites that convert web pages to PDF's for free
after research, here is what i have found. Adobe Acrobat Pro have that BUILD IN. reference : http://www.adobepress.com/articles/article.asp?p=1252827&seqNum=3%C2%A0 and http://www.pdfforlawyers.com/2005/12/how_to_create_a.html. information date back from 2005 and 2008!