Stephen Vincent's Plug-ins - Offers various plug-ins with a theme of creating complex paths in Adobe Illustrator. - http://members.shaw.ca/spvincent/plugins/
Panopticum - Offers plug-in modules for Illustrator for creating complex geometrical patterns and vectorizing color raster images. - http://www.panopticum.com/products_ai.shtml
ILLOM Toolbox 1 - Various plug-ins tools like Search/Replace, Selection tools, Time tracker, Type Style Library, Transform and Magnet tools, and a game as a plug-in for Illustrator. [Mac/PC] - http://www.illom.se/prod/tb/tb1/
Graffix - Choice of multiple plugins for Adobe Illustrator 7 and above for download. - http://rj-graffix.com/software/plugins.html
Vectorization plugin for Adobe Illustrator - Plugin to convert bitmap images to vector images with unique correction tools for Windows and Mac. - http://www.silhouetteonline.com
Hot Door Inc. - Offers various plug-ins for Adobe Illustrator including CAD, simulated 3D drawing, and symbols. - http://www.hotdoor.com/
Network Symbol Library Plug-in - NetZoom Symbols is a powerful plugin for Adobe Illustrator to easily create detailed and accurate network diagrams, network documentation, proposals and presentations using over 35,000 vector network equipment symbols. - http://www.altimatech.com/static/nzforadobeillustrator.php
Virtual Mirror Corporation - Developer of Vector Studio a collection of six Illustrator plugins, including Envelope Mesh and Morph Brushes. - http://www.virtualmirror.com/
MapStudio Web - Plugin to draw orienteering and other maps. The plugin is only for Macintosh. - http://www.innovad.net/mapstudio/
Magisign - Produce signs in 4 steps using Adobe Illustrator. - http://www.magisign.com/
CVally, Inc. - Offers three plug-ins for Adobe Illustrator. FILTERiT, Xtream Path, and Silhouette. - http://www.cvalley.com/
Artlandia SymmetryWorks - Adobe Illustrator plugin that lets you easily creates and interactively edits symmetrical patterns and designs. Available for both Mac OS and Windows. - http://www.artlandia.com/products/SymmetryWorks/