I've played around with PKI's on my home network and you can actually come to my server and get a digital certificate. But I need to have a level of knowledge that extends deeper than "I've dinked around with it a bit."
This being the case, I went to Amazon to look for books on PKI. I found a Microsoft Press book specifically on PKI's (which was exactly what I wanted). What really amazed me though was a new feature on Amazon called Statistically Improbable Phrases. You can see this section by going to the book link here. Let me quote from Amazon's description of what Statistically Improbable Phrases tells a user of Amazon:
Amazon.com's Statistically Improbable Phrases, or "SIPs", are the most distinctive phrases in the text of books in the Search Inside!TM program. To identify SIPs, our computers scan the text of all books in the Search Inside! program. If they find a phrase that occurs a large number of times in a particular book relative to all Search Inside! books, that phrase is a SIP in that book.This is simply incredible to me. The sheer processing power and comparitive indexing required to pull this highly-useful reference off is mind-blowing to me. Staggeringly brilliant and useful.
SIPs are not necessarily improbable within a particular book, but they are improbable relative to all books in Search Inside!. For example, most SIPs for a book on taxes are tax related. But because we display SIPs in order of their improbability score, the first SIPs will be on tax topics that this book mentions more often than other tax books. For works of fiction, SIPs tend to be distinctive word combinations that often hint at important plot elements.
Click on a SIP to view a list of books in which the phrase occurs. You can also view a list of references to the phrase in each book. Learn more about the phrase by clicking on the A9.com search link.
Amazon and Google are the two most deeply, meaningfully useful sites on the web.