Best libraries for my project.

[eluser]Unknown[/eluser]
Hello, im working on my new project.
the address is : http://www.mythunt.com

When i started to work on this project, i didn't know much about codeigniter Libraries & Helpers.
Now, after i programmed half of my site, i feel a little stupid that i could use these nice Libraries to make it easier for me to program.

I want to rewrite my code. For this, i would like to know what are the best libraries for my needs.
My site uses alot of AJAX, FaceBook.

I also seen DataMapper which looks like a great tool.

What Libraries & Helpers do you recommand me to build my website with?