sdvplayer is a tool to help you improve your vocabulary in a foreign language by watching movies with subtitles in that language. It allows you to look up the meaning of a word displayed in the subtitles just by clicking on it. The meaning will be printed right on the screen and the player will be paused. Playing can be resumed just by pressing the space bar. It can play movies in many of the formats supported by libav*. Subrip (.srt), microDVD, and subviewer subtitle formats are supported. The meaning can be looked up through an external command. The built-in dictionary parser can parse the stardict dictionary format.
seaLISP is a Lisp interpreter with as many bells and whistles as possible but with absolutely no dependencies apart from the C++ standard library. The garbage collector, the computer algebra library, and all other components are written from scratch to be portable. It also has a PSP port with some primitives for graphics.
sec-wall is a feature-packed security proxy that supports SSL/TLS, WS-Security, HTTP Auth Basic/Digest, extensible authentication schemes based on custom HTTP headers and XPath expressions, powerful URL matching/rewriting, and an optional header enrichment. It's a security wall with which you can conveniently fence otherwise defenseless backend servers.
Seetxt is a lightweight text file and man page viewer for X windows. It maintains "document meta-data" for each user, allowing them to automatically keep bookmarks and highlights for read-only system files. It also has a "server mode" so that command line requests can be sent to a single running server rather than starting multiple instances. Other features include hypertext-style apropos (man page) searches, file monitoring, multi-level regular expression searching, a command history, and nice little toggle lights on the interface for the server and file monitor. There's also cross-application drag-n-drop support, and handy little features that allow you to view the output of shell commands and process the text buffer with an external command (sed, awk, grep, perl, etc.) Seetxt is POSIX compliant.
Sefira library is meant to provide a well tested and reasonably optimized implementations of some tree comparison algorithms, so that they can be tried out in practical applications. Finding the largest common subtree of two ordered labeled trees is a problem with increasing applications (e.g. in XML processing and computational biology), on which substantial progress has been made in recent years. However, papers on tree comparison may not be available without subscription to the appropriate journals and even when they are, they generally don't contain executable code, so using the new algorithms is non-trivial. Also, there isn't one "best" algorithm yet. Distance definitions differ, and even for the same edit distance, time complexity can be measured on different tree features.
selector is a command line utility for dynamic string selection. As you type a list of substrings separated by ";" or a regexp, the display is updated in real time to show only the matching lines. The main usage of selector is as an efficient search in the shell command history. With the correct option, it will inject the selected line into the terminal input buffer, allowing the user to edit the line and execute it as a standard command.