DIMIDIUM FACTI, QUI COEPIT, HABET
Our suggestions
Concatenate MIDI files
Perl software distributed under the GPL that does simple transformations on MIDI files.
Columns filled with numbers turned into images
ECMAScript (Javascript) library, distributed under the GPL license, that creates charts from (x)HTML tables.
Your mailing lists available through the web
GPL-distributed PHP software which transforms mailing list archives to W3C-compliant web pages.