The Mnemosyne software resembles a traditional flash card program to help you memorize question/answer pairs, but with an important twist: it uses a sophisticated algorithm to schedule the best time for a card to come up for review. Difficult cards that you tend to forget quickly will be scheduled more often, while Mnemosyne won't waste your time on things you remember well.
Foswiki is wiki software, supporting the editing of Web pages in an ordinary Web browser by end users. What makes Foswiki special is that it supports the embedding of active and passive macros that enhance the page content (e.g. with global or dynamic information) and allow end-users to build applications that store and process data in a structured manner.
linSmith is a Smith charting program. Users can enter either discrete components or transmission lines, see the results on screen, and/or generate Postscript output. Component values can be changed numerically or using scrollbars. Problems can be solved on-screen, and high-quality Postscript can be output for publication.
Ekiga (formely known as GnomeMeeting) is a soft phone, video conferencing, and instant messenger application for use over the Internet. It supports HD sound quality and video up to DVD size and quality. It is interoperable with many other standards compliant software, hardware, and service providers as it uses both of the major telephony standards, SIP and H.323.
Spotter is software that can check students' answers to symbolic and numerical problems in math and science. It recognizes an answer regardless of the form it's in, and the instructor can put in helpful hints as responses to frequently-occurring mistakes. Symbolic answers can be input in a notation closely resembling normal human math notation (e.g., xy rather than x*y, and sin x instead of sin(x)). Spotter runs as a Perl CGI application on a Web server; the student doesn't need to install any software.