pcal is an old but well updated postscript calendar generator. It has lots of bells and whistles to print nice looking calendars. You need to provide your own photos to put above each page, though. :^) lcal is a companion utility that prints lunal phase calendars.
dead link: http://www.sunpoint.net/~pcal/
This tool makes church front announcement signs with up to four lines of your own text.
dead link: http://www.aboyandhiscomputer.com/churchsigngenerator/index.php
2020 Update: That site has apparently changed hands. There are similar sign generators out there, but not that one. Red Kid has a variety of formats including a similar school sign and Big Boy diner, and Oakland Grand Lake Theatre. A footnote says the site is based on the original code.
A large collection of specifications for computer cables and connectors. A little out of date, but good for older devices.
dead link: http://hardwarebook.net/
2020 update. Fixed link,
but the new site is kinda broken, like it's missing a style sheet.
And it gives completely different
content for http:// (real but broken) and https://
(a default site template).
This is my favorite image viewer. It has the standard features such as thumbnail views and slideshow modes, but it also can fetch files with wget and reload periodically for webcams, etc.
dead link: http://www.linuxbrit.co.uk/feh/
qz thoughts