Drupal is a popular content management system containing a library of PHP functions useful for making all sorts of web sites. This page indexes some of the Drupal-related things that I have produced and/or maintain.
Modules
Since Drupal loads all modules on every page view, I prefer modules that are small. If these modules happen to do what you want, you might find them useful. If they don't, understand that the lack of configuration UI is intentional. Maybe one day configuration hooks will be split out of the .module file the way that install/upgrade/activate hooks are in a separate .install file. I may reconsider my thinking then.
- redirect_callback: creates a path which simply takes a URL as a parameter and redirects to that URL. For logging outgoing clicks in your web server logs.
- markasread: allows a user to mark all forum topics, or all topics in a particular forum as read.
- contact_nocc: removes the "Send yourself a copy" checkbox from contact forms
- metakeyword: allows the setting of a default set of keywords for the whole site and allows individual pages to add to that set.
- twitter: posts to twitter when a story node is posted
- forum_sticky_mod: Creates an access permission for a moderator role that is allowed to set sticky forum posts (like for announcements)
- opensearch_link: Adds a opensearch autodiscovery link to all pages
Memory Reduction Modules
Drop in replacement for existing modules which reduce memory usage and possibly make your drupal site faster.
- system: drop in replacement for the Drupal core system.module, but faster in many configurations by using less memory.
- taxonomy: drop in replacement for the Drupal core taxonomy.module, but faster in many configurations by using less memory.
- watchdog: drop in replacement for the Drupal core watchdog.module, but faster in many configurations by using less memory.
- pathauto: drop in replacement for the Drupal contributed pathauto.module, but faster in many configurations by using less memory.
- event: drop in replacement for the Drupal contributed event.module, but faster in many configurations by using less memory.
- spam: drop in replacement for the Drupal contributed spam.module, but faster in many configurations by using less memory.

Gread! Load times cut!
Thank you very much. We had one site with extreme loading times that could not be identified. Your code has cut the loading times up to 70% !
Drupal 6.x does that, and acclerators lessen its impact
Drupal 6.x does that already, and acclerators lessen the impact of such code. Why not contribute those as patches on drupal.org? Please see my comments here and here.
I had been assuming
Do the memory reduction modules actually hurt performance with an opcode cache enabled?
I had been assuming (incorrectly?) that such large patches would not get accepted into Drupal 5