Vector Based

Adobe FreeHand
An award winning tool for creating illustrations and layouts for print or for the Web designs.
http://www.adobe.com/products/freehand/

Celedy Software Inc.
Draw and publishing software for small businesses and home users. Tutorials, FAQs, downloads, and samples.
http://www.celedy.com/

CompactDraw
Create flexible vector graphics in real time, with the appearance of BMP textures, shadows, lights, transparencies, bevels, and other 3D effects. 30-day trial.
http://www.mediachance.com/compactdraw/index.htm

Creature House
Software developer of Expression, LivingCels, and author of Skeletal Strokes. Expression is a vector drawing program with 'Skeletal Stroke' technology which stretch or repeat across the length of a vector path to create anything from natural media brush strokes to a field of flowers.
http://www.creaturehouse.com/

A Graphical Finite State Machine Editor
Qfsm is a graphical tool for designing finite state machines. Written in C++ with Qt. For Linux/Unix. GPL.
http://qfsm.sourceforge.net/

How to draw vector prismatic letters
Tutorial explains step-by-step how to create faux 3 dimmensional lettering (also known as prismatic) using any vector-based illustration program.
http://www.letterheadfonts.com/tipsandtricks/prismaticeffects/

Ipad-Pro
A multiplatform front end to an interactive GUI vector drawing package. Supported Platforms: Solaris/Linux/MSDOS/OS/2 Warp/Windows 3.1/95/98/NT.
http://xcprod.com/titan/

ITEDO Software GmbH
Offers the IsoDraw and IsoView software for technical illustrations, with news, introductory information about the topic, and practical tips for illustrators.
http://www.itedo.com/

ivtools Drawing Editors
Collection of free X Windows drawing editors for vector-graphics production, and a layered application framework for custom direct-manipulation graphical editors.
http://www.ivtools.org/

jfig
A 2D graphics and diagram editor written in Java and based on xfig. Includes download and documentation.
http://tams-www.informatik.uni-hamburg.de/applets/jfig/

Mayura Draw
Vector based drawing program for Windows. Export to EPS, AI, PDF, WMF, GIF, BMP, TIFF. Import AI and WMF.
http://www.mayura.com/

NetZoom Symbols for iGrafx Process and Flowcharter
Network equipment symbol library for iGrafx offering over 50,000 detailed vector-based graphic images. All images/icons are vendor-specific representations of computer and telecommunications networking equipment.
http://www.altimatech.com/static/nzforigrafx.php

Random Pattern Generator - UZII
UZII is a random pattern generator that draws various vector patterns. Provides a gallery of patterns for backgrounds.
http://uzii.narod.ru/

Serif DrawPlus 8
Illustration software with 200 vector and bitmap brushes, various photo effects, design templates and red eye removal. [Windows]
http://www.serif.com/drawplus/drawplus8/index.asp

SkechLaTeX Plugin
Plugin allows LaTeX text or equations to be inserted into a Sketch document as native text objects.
http://www.2pi.info/latex/sketchlatex/index.html

Skencil
A fully functional vector-based drawing program for Unix, written in Python. Imports XFig, AI, CMX, WMF and SVG formats. Exports AI, PDF, SVG, EPS and PS formats.
http://www.skencil.org

Sodipodi
Archived source and executable downloads for this Inkscape predecessor.
http://sourceforge.net/projects/sodipodi

Tech Illustrator
Windows NT-based technical illustration software that includes data exchange converters and filters, text processing for graphics, and on-line help. TI complements CAD/CAM software through direct repurposing of existing 3D design data.
http://www.tech-illustrator.com/

VG.net
Animated vector graphics for .NET developers. Includes a graphics editor integrated in Visual Studio .NET.
http://www.vgdotnet.com/

Weresc CAD Control
ActiveX control to view and edit 2D vector graphic. CAD Control utilizes the common AutoCAD DXF format. It is optimized for size and performance and could be used to display graphic on web.
http://www.weresc.com/

xfig
Drawing program for the .fig format. Software download and related documention, libraries, drawings, and pointers.
http://www.xfig.org/

ZONER, Inc.
Zoner Draw 4 is a vector graphics editor fit for all users and uses: create impressive leaflets, illustrations, business cards, letterheads, postcards, titles, maps, and greeting cards. Also produces rich Internet graphics. Download Zoner Draw's 3 for free.
http://www.zoner.com/