The Wikiquote.org website collects quotations and they have a lot of nice ones.
There already exists a screensaver for windows that displays quotes from this website, called WikiquoteScreensaver.
The WikiquoteScreensaver actually has a very cool and powerful (C#) configuration tool for letting you search for and download quotes you like from the site, and then saves them into data files that the screensaver uses offline.
Since they did such a great job with the quote search/downloading tool, what i decided to do was just add support for reading the data files to the Multi Photo Quotes screensaver.
So if you want to add quotes from Wikiquote.org to Multi Photo Quotes, install the WikiquoteScreesaver from their website, and download some quotes, and then save the .wqxs file(s) with your downloaded quotes into a Books\ subdirectory, and MPQ will read them as normal.