Analog
The most popular logfile analyser in the world is now free. Analog measure's your website activity by telling you which pages are most popular, which countries people are visiting from, which sites they tried to follow broken links from, and all sorts of other information. You can buy WebTrends for $1600+ or use Analog for free. The latest version of Analog can always be found here

PDFCreator
PDFCreator is a free tool to create PDFs easily from nearly any application. With the PDFCreator Printer driver you turn any program into a PDF-machine. PDFCreator offers multilingual support, so anyone who wants to contribute a language can edit one text file and enjoy his own language. PDFCreator is released under the term of th GPL (GNU General Public License). The newest version of PDFCreator can always be found here.