Remem (The Remembrance Agent) is a plug-in developed and maintained by Bradley Rhodes, for Emacs (a Unix-based text editor), which suggests information relevant to what you’re currently reading or writing.
It is a cursor based tool that helps with associative memory, unlike search tools that help with direct recollection. The plug-in is available as a TAR and GZIP file and requires GNU Make to compile.
The site also contains useful research documents on the tool and associated topics on intelligent user interfaces.