Links
PDF development (1). This is interesting if you are a developer: Bruno Lowagie's and Paulo Soares' iText. A great free (!) Java library for creating and manipulating PDF's. Also available for .NET. This is how I got in playing with C# (and now also Turbo Delphi for .NET).
PDF development (2). Another one that may interest you if you are a developer and need to create PDF's from your applications: the Haru Free PDF Library. A library for C developers; but also includes an interface for Delphi/Free Pascal.
PDF development (3). Like they say: iSEDQuickPDF is the easiest way to get powerful control of PDF documents in your applications. Available as an ActiveX library, a DLL and as a Delphi class. Note this library is not free, and the support from the supplier is poor. Fortunately there's an active usergroup (see second link).
Chicks' PDF tools. Chicks is a rabid user of Sid Steward's PDF Toolkit. He has created a couple of interesting PDF tools and support tools (a.o. one for reordering pages in a PDF) that you might like as well.
PDF (Rumborak) This site (German language) is a good starting point if you need to know more about PDF and PostScript and many of the tools available.
Concatenate (join, merge) PDF's (1). A simple tool made by Ujihara Kazuya, based on iText, that can join PDF files, extract pages from PDF files; again functions for which you would have to buy expensive Acrobat otherwise.
Concatenate (join, merge) PDF's (2). Andrea Vacondio made another merge & split tool for PDF's, also based on iText.
TIFF to PDF converter. This command line utility offers extremely fast "conversion" (wrapping) of TIFF files to PDF.
Delphi development. Angus Johnson's very useful tips and components. For instance his GetPdfPageCount code is used in one of my PDF tools, his drag&drop Delphi VCL's in a couple of other tools.
WinVi Text & HEX editor. A simple editor that can edit almost any file (text & binary). I use this very often to quickly check the content of files ("what type of file is this"; "why isn't it doing what I expected") and for minor changes in a.o. plot files.
AutoCAD. Jimmy Bergmark's site offers useful tips, scripts and AutoLISP routines. I found his PlotDeviceFunctions AutoLISP routine very useful to avoid the annoying "None" device and "None" plot style when plotting other people's AutoCAD drawings.
Image viewing. Irfanview. A popular free viewer and converter for raster images. Also useful for batch conversion of image files. Post-process TIFF G4 files with C42PDF (see above) to convert to PDF. Use the PDF toolkit or GhostScript and my GoBatchGS GUI to merge the PDF's into one multi-page PDF file.
Web browsing. Firefox .... Forget Internet Explorer; here's the better alternative for web browsing.
More free tools. Find more free tools and programs at the Freeware World Team's site.
File formats. A wealth of information on all sorts of file formats.