Implementations

Ambrai, Inc.
Makes Ambrai Smalltalk, rapid application development platform to make new, or script extant, Mac OS X programs. Descriptions, documents, downloads, contact page.
http://www.ambrai.com/

Cincom Smalltalk
Information on ObjectStudio, VisualWorks, VisualSmalltalk Enterprise; general Smalltalk information and success stories.
http://www.cincomsmalltalk.com/userblogs/cincom/blogView

F-Script Home
Smalltalk-based pure object-oriented environment to work with Mac OS X software. Innovations: high-level model for object manipulation, powerful object browser. Developed from scratch for the Objective-C object model. Highly integrated with Cocoa, native access optimized. Descriptions, news, documents, downloads.
http://www.fscript.org/

GemStone/S
Smalltalk application server, integrates well with Java, CORBA, relational databases.
http://www.gemstone.com/products/smalltalk/

GNU Smalltalk
Official Page at Smalltalk.org: very brief description, 8 links to varied resources. [Open Source, GPL]
http://www.smalltalk.org/versions/GNUSmalltalk.html

GNU Smalltalk
Smalltalk-80 implementation, runs on most Unix types and most places with a POSIX compliant library, well suited to scripting tasks and headless processing. Part of GNU Project of Free Software Foundation, FSF. [Open source, GPL]
http://www.gnu.org/software/smalltalk/smalltalk.html

LSW Vision-Smalltalk
A Smalltalk with deep Windows integration and a .NET interface. [Commercial]
http://www.lesser-software.com/lswvst.htm

LSWVST.Net
Pure .Net Smalltalk, Win32 counterpart uses CLR moniker to integrate with .NET, integrates deeper than other Smalltalks. Runs on: all .NET platforms (DotGNU, Microsoft .NET, Mono), varied processor architectures, the Compact Framework.
http://www.lesser-software.com/en/content/products/lswvst/lswvst-net.htm

Minimal: Little Smalltalk
Very small, interpreter under 1,800 lines, has no graphics. Topic of classic Addison-Wesley book 'A Little Smalltalk'. Both by Timothy Budd, Oregon State University. [Free for non-commercial use]
ftp://ftp.cs.orst.edu/pub/budd/little/index.html

Minimal: Tiny Smalltalk
Download for VSTa operating system, tar file.
http://www.vsta.org/distro/current/small.tz

Object Connect: Smalltalk MT
High quality development tools for Windows market: innovative, high-performance, small runtime image, fully multithreaded. Interactive development environment with no sacrifice of runtime performance and deliverable size: compact, fast, royalty-free executables. From France.
http://www.objectconnect.com/

PIC/Smalltalk
Custom Smalltalk variant for the PIC microcontroller to run the MicroSeeker autonomous underwater vehicle.
http://www.huv.com/uSeeker/smalltalk/pic.html

Pocket Smalltalk
Makes programs for PalmPilot, other Palm OS handhelds. Development environment runs on Linux, MacOS, OS/2, and Windows 95/98/NT/2000. Cross-compiler generates executable .PRC files from source code. [Open Source]
http://www.pocketsmalltalk.com/

Satori
To be a superset of Smalltalk-80 with optional variable typing, to allow typechecking of variables and static binding of methods. Typechecking helps ensure type-safe code. Static binding cuts runtime expense, for more speed.
http://www.zenspider.com/Satori/

#Smalltalk
sharp-Smalltalk compiler implements Smalltalk to run natively on .NET framework, allows using classes from normal .NET programs; class library is mostly compatible with ANSI Smalltalk. [Open Software License]
http://www.refactory.com/Software/SharpSmalltalk/

Smalltalk Archeology Archive
Has old variants: Apple Smalltalk-80, Digitalk Methods and Smalltalk/V; descriptions, screenshots, downloads, documents.
http://bitquabit.com/~revaaron/old/

StepTalk
Smalltalk interpreter for GNUstep, used mainly as scripting framework to make scriptable servers or programs, to script GNUstep applications, or to talk to registered distributed objects, and work well with Objective-C. [Open Source, GPL]
http://www.gnustep.org/experience/StepTalk.html

StepTalk
Weblog on scripting, StepTalk development.
http://steptalk.blogspot.com/

Strongtalk
Strongly-typed, full rework of Smalltalk-80. Advanced inlining type-feedback compiler makes it far faster than other Smalltalks, optional type system makes it easier to understand. History, downloads, documents, FAQ. [Open Source, Sun]
http://strongtalk.org/

Susie
Project information: CVS, changes, downloads, mail list. [SourceForge.net]
http://sourceforge.net/projects/susie/