AVL and TST trees implementation
Richard's Lair
http://dasnar.sdf-eu.org/miscres.html

Citrus: BSD I18N Framework Implementation Project
The project is writing libraries and tools with non-restrictive licensing for internationalization and localization of UNIX software. This includes a Locale/iconv implementation to conform to ISO C/SUSV2, gettext and POSIX NLS catalog implementation.
http://citrus.bsdclub.org/

Smalltalk-80: The Language and Its Implementation
Part 4: The Implementation, Chapters 26-30; defines full reference implementation for original 16-bit Smalltalk-80 Virtual Machine needed to run image. Code is all Smalltalk, written for clarity, not speed; optimizations left to implementors. [Online]
http://users.ipa.net/~dwighth/smalltalk/bluebook/bluebook_imp_toc.html

Multics Emacs: The History, Design and Implementation
Classic paper describing thie history and design of Multics Emacs.
http://www.multicians.org/mepap.html

AED Implementation
Automated External Defibrillator Implementation Products and Service.
http://www.ernetwork.com

Scheme 48
A small and portable implementation based on a bytecode interpreter designed to be used as a testbed for experiments in implementation techniques.
http://s48.org/

Point Consulting - Implementation package
ISO 17025 package including quality manual, procedures and quality records for implementation of the ISO 17025 accredition requirements.
http://www.17025.homestead.com

Yet Another SSL
The yaSSL software package is an open source, dual licensed implementation of SSL. It includes SSL client libraries and an SSL server implementation.
http://www.yassl.com

Implementation of DBC
Document and source code on implementation of DBC for CLOS.
http://www.muc.de/~hoelzl/tools/dbc/dbc.lisp

Turnkey Consulting
Specialises in the implementation and review of SAP Security and Portals solutions as well as expertise in the implementation of the Governance, Risk and Compliance (GRC) product range.
http://www.turnkeyconsulting.co.uk