Apago  
   Offers a full line of software products for the graphics and pre-press industries. Apago has several plug-ins for PDF.
   http://www.apago.com/products.html

Lantana Research Software  
   Developers of plugin tools for creating layers, increasing form usability, color production printing, image editing.
   http://www.lantanarips.com/

Merlin Open Systems  
   Developer of cross-platform Adobe Acrobat plugins.
   http://www.merlin-os.co.uk/

PDF Snake  
   Adobe Acrobat plugin that adds imposition, scaling, watermarking and other features.
   http://www.pdfsnake.com/

PDF Solutions  
   Clonelinks plugin for Adobe Acrobat 4, allowing easy copying of attributes between PDF links.
   http://www.clonelinks.com/

Quite Software  
   Developers of plugins, such as Quite A Box Of Tricks, Quite Imposing, and Quite RGBGone.
   http://www.quite.com/

Convert Zone  
   Adobe Acrobat plug-ins and batch programs to convert between pdf, doc, html, excel and text files.
   http://www.convertzone.com/

PDF Everywhere  
   Provider of a set of software PDF products files: merging, splitting, encrypting, decrypting, stamping, imposing, and extracting of PDF files without using Acrobat products.
   http://www.pdfeverywhere.com/

PDF to TEXT Converter  
   Plug-in for Acrobat that converts PDF to text, HTML, bmp and jpg. Software descriptions, screenshots, FAQs, demo downloads, and contact details.
   http://www.pdftoall.com/pdf%20magic.htm

PDFtoALL  
   Plug-in that converts PDF files to text, HTML, BMP, JPG and PNG. Information and demonstrations available for download.
   http://www.pdftoall.com/

LineType Software, Inc.  
   LineScale plug-in for Acrobat and Acrobat Reader is the premier distance and area measuring tool for PDF files, offering unique features in an easy-to-use interface. Electronic document solutions and consulting services for architects, engineers and contr
   http://www.linetype.com/

Appligent  
   Provides tools for personalizing, stamping, appending, splitting, merging, manipulating, signing and securing PDF files on all leading server platforms. The Redax plug-in provides foolproof redaction of sensitive content from PDF documents.
   http://www.appligent.com/

Creo  
   Developers of plug-ins, such as Pagelet, and PDF Seps2Comp. Plug-ins allow to transform separated PDF files into composite documents.
   http://www.creo.com/global/products/software_solutions/creative/default.htm

ReaderSave  
   Plug-in to retrieve past Adobe Reader form data
   http://www.siquis.freeserve.co.uk/

Datafarm Inc.  
   Developers of Acrobat Plug-ins and other PDF tools.
   http://www.datafarminc.com/

Evermap  
   AutoSplit plugin for acrobat.
   http://www.evermap.com

IntelliPDF  
   Adds Bates Stamps to PDF documents.
   http://www.intellipdf.com