SQL Tagger reads the tags of audio files from a directory, loads them into a temporary SQLite database, accepts SQL queries to modify this database, then saves any changes back to the audio files. It's useful for performing complex updates that would be difficult or tedious with conventional taggers. It's a complement to conventional taggers, not a replacement.
waitcond is a script to specify a combination of events using boolean expressions over various events. It can periodically grep in files, wait for the (dis)appearance of files or processes, wait for certain CPU/net/disk idle values, or wait for an idle tty. waitcond is meant to be combined with some notification tool or system.
tagls is a tool that matches file names using boolean expressions made of tags and regular expressions. It handles searching in file lists with word boundaries for "tags", stemming and synonym expansion for both tags and regular expressions, and boolean expressions over lists of tags or regular expressions. It can match against either the file name or the file's content. The output can be unsorted, sorted by name, or sorted by relevance.
selector is a command line utility for dynamic string selection. It reads the content of the specified files, and as the user types a list of strings separated by ";" (or a regexp), the display is updated in real time to show only the lines containing all the said strings (or matching the regexp). This command was mainly designed as a way to search in the shell history, for which it is substantially more efficient than the standard readline ^R binding. With the -v option, it injects the selected line into the tty input buffer, hence allowing the user to edit the line and execute it as a standard command.
surl is a URL shortening command line application that supports various sites. It supports stdin or filename input. It grabs the URLs, converts them, and returns the same text that was used in the input. It is known to work with a wealth of services, such as bit.ly, tinyurl.com, and others.