GNU libmicrohttpd is a small C library for embedding HTTP server functionality into other applications. It is reentrant, fast, supports HTTP 1.1, and permits listening on multiple ports. The API is simple and still powerful enough to allow programmers to use the entire HTTP feature set. SSL/TLS support is available as an option.
Gow (GNU On Windows) is a lightweight alternative to Cygwin. It uses a convenient Windows installer that installs about 130 extremely useful open source Unix applications compiled as native Win32 binaries. It is designed to be as small as possible, about 10 MB, as opposed to Cygwin which can run well over 100 MB depending upon options.
BaseX is a light-weight, high-performance, and scalable XML database system and XPath/XQuery processor, including full support for the W3C Update and Full Text extensions. An interactive and user-friendly GUI frontend gives you great insight into large XML data instances. It is platform independent and works out of the box.
DB Solo is a powerful database development and management tool for developers and DBAs. It has an intuitive user interface that allows you to explore and manage your database objects as well as execute ad-hoc queries. It supports Oracle, MySQL, Sybase, DB2, Solid, PostgreSQL, and MS SQL Server. In addition to viewing and managing objects such as schemas, tables, indexes, views, tablespaces, users, roles, sessions, and stored procedures, you can view, edit, print, and export data from tables or the results of queries. You can also graphically view foreign key relationships.
The stunnel program is designed to work as an SSL encryption wrapper between remote client and local (inetd-startable) or remote server. It can be used to add SSL functionality to commonly used inetd daemons like POP2, POP3, and IMAP servers without any changes in the programs' code. It will negotiate an SSL connection using the OpenSSL or SSLeay libraries. It calls the underlying crypto libraries, so stunnel supports whatever cryptographic algorithms you compiled into your crypto package.
GeoToad is a geocaching query tool to help speed up the boring part of geocaching: choosing the cache and collecting the data. It allows you to generate any kind of complex query you want, and the program will go and poll the Geocaching query, grab the data, and output it to any format you want. The Geocache info can be synced straight to your GPS, iPod, PDA, or cell phone in over 20 different formats.