JavaScript Corral 
Lasso yourself some cool and useful free JavaScripts at this fast-loading, helpful site. Here, you'll find JavaScripts for pop-up images, mouse-over effects, clocks, scrollers, dates, menus and more. Just cut and paste the scripts you want. The site includes tutorials and instructions for implementing the scripts.

JavaScript Kit 
A regularly-updated resource for free JavaScript and Java, this site offers over 300 free scripts and Java applets and a very active JavaScript forum where developers can meet and discuss their script projects. There are also handy tutorials here, where you can learn JavaScript, DHTML and Webmastering.

CodeHouse.com 
This well-designed site serves up a nice selection of free JavaScript resources. Here, you'll find free scripts, online tools, articles, bookmarklets and other resources aimed at programmers and Webmasters. CodeHouse.com also offers free resources for JavaScript-related technologies, such as DHTML, CSS, XML and more.

Nic's JavaScript Page 
A handy resource for free JavaScripts. The code you'll find here is compact, (which makes it easier to manipulate and learn from). This is a well-organized site, so you can quickly find what you need. (Note: this site has been occasionally inaccessible recently).