libNog is a 9k library to provide somewhat easier browser-independence. It is not yet complete, and will be continuously revised. It grew from this snippet, and is still growing as I find things I use often.
Presently, libNog features:

A way to browser-independently get an XMLHttpRequest object.
A set of simple methods for GET, POST, HEAD, and to include other Scripts.
Simple methods for className control
A completely abstracted form of getElement*
Browser-independent methods for attaching and detaching event handlers
An event-normalization routine
A simple one-command 'Stop the Event' routine
And the big one: A simplified Class object by which classes can be built in JavaScript.

The above link will point you to the API documentation and history of libNog, as well as where to download the library.

Return object by type. Revision 2.

Return object by type

Remove all children of Object.

I like to have these two methods in my toolbelt, even though it's syntactic sugar, I think it aids clarity.

Just a small snippet I discovered when I was tired writing somearrayname\[i\] I thought there was something like foreach in javascript but couldn't find any so why not make one?
For those foreach(){...} lovers.

Hope it makes your life easier.

Simple chatting script to be placed on a corner of a website
Also a good example how to use ajax.

Highlight table row on rollover.

There seems to be so many hide/show scripts out there, so here's the functions I wrote and use on a regular basis - there are 7 functions, hide, show and toggle by id or class - and the getElementByClass function that does not exist as a built in Javascript function...

This is in response to the flurry of visibility scripts that just don't have all the pieces needed to make them totally useful.

An easy way to hide and show div's using Javascript and CSS.

Basically just a slight variation on this script by Real Gagnon.