Links
If you need to understand and browse the internal structure of a PDF document, then the PDF Crystal tool is indispensible.
Don't have Adobe Acrobat? Click here to go to Adobe Acrobat's home page.
Looking for some other PDF tool? Click here to visit PDF Store. They have hundreds of tools.
Printers.resourceaid.com has collected a list of nearly every printer hardware and software that a print shop could want.
Working with e-books? Click here to visit Max EBook, which has articles about e-book topics, and a directory of tools.
Need to convert Word, Excel, or Powerpoint to PDF? Try PDF Convert.
Off topic, but if you're looking for neural network software, Neuromine is the best I've seen.