o - is simple lightweight JavaScript library for basic object manipulation. Compressed and gzipped weights around 0,5 kb. It should work on IE 5.5 and latter. Also there is lite version that doesn't make hasOwnProperty check that will run faster and with less code.
Learn more on: http://vladocar.github.com/o---JS-Library-for-Object-Manipulation/
The object methods can be found here (Object Auto Documentation): http://dl.dropbox.com/u/2111778/AutoObjectDocumentation/demos/autoDocs-o-prettify.html