Scrips written by other people

Scriptopedia by Loic Aigon, check out also this page and his blog

Indiscripts by Marc Autret

Kahrel+ by Peter Kahrel

In-tools by Harbs and by Marijan Tompa

JavaScripting InDesign -- Dave Saunder's blog

Adobe Add-ons (formerly known as InDesign Exchange)

InDesign Master by Boris Kashcheev and Mikhail Ivanyushin (in Russian)

InDesign automatisieren by Gregor Fellenz (in German) (in German)

Scripts for Photoshop and Bridge created by Paul Riggott