A really nice collection of JavaScript tools and scripts can be found here

http://www.smashingmagazine.com/2008/09/11/75-really-useful-javascript-techniques/

80+ AJAX-Solutions For Professional Coding

60 More AJAX- and Javascript Solutions For Professional Coding

30 Scripts For Galleries, Slideshows and Lightboxes

40+ Tooltips Scripts With AJAX, JavaScript & CSS

Data Grids with AJAX, DHTML and JavaScript

All these resources are very good and certainly something here for everyone.