Grep.pm is a much-modified fork of tcgrep. It understands context, matching from the start or end of a file (with a line count or byte count), and features size limits and highlighting. It extends matching to boolean expressions, structuring regular expressions, or even arbitrary pieces of Perl code. It can perform basic stemming and synonym-expansion in regular expressions (using expansyn). It also handles \0-lines, paragraphs, file slurping, directory recursion, and compressed files. It can act either as a Perl module or a command-line program. Grep.xchange is a support program taking grep or Grep.pm input and applying an expression at each grep match to the files specified in the grep output. This expression can be arbitrary Perl modifying e.g. just the line of the match with s///g, or operate against the current pos() position in the whole file. Grep.xchange --modified goes one step further and replaces the matched lines with the (edited) text from the grep output. Changes are logged in diff -u format and can be revoked/redone with patch.
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.
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.