Text auto-complete: http://devthought.com/textboxlist-meets-autocompletion/

Links from Smashing Mag:

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

http://www.smashingmagazine.com/2009/02/08/50-extremely-useful-javascript-tools/

http://www.smashingmagazine.com/2008/04/15/60-more-ajax-and-javascript-solutions-for-professional-coding/

http://www.smashingmagazine.com/2008/09/16/jquery-examples-and-best-practices/