Word 2008 has a notebook mode which is very nice --- may work for your needs.
Other Mac OS X programs like to OneNote:
Aquaminds NoteTaker ---
http://www.aquaminds.com/index.jsp
OmniGroup Outliner ---
http://www.omnigroup.com/applications/omnioutliner/
Circus Ponies Notebook ---
http://www.circusponies.com/
Zengobi Curio ---
http://www.zengobi.com/products/curio/
Mariner Software Mac Journal ---
http://www.marinersoftware.com/sitepage.php?page=85
Journler ---
http://journler.com/
Notemind ---
http://www.synium.de/products/notemind/index.html
MyNotes ---
http://www.mishimo.com/mynotes
Mage Software InkBook ---
http://www.magesw.com/inkbook/
SOHO Notes ---
http://www.chronosnet.com/Download/s..._download.html
Some people use the Zotero plug-in for FireFox to manage their research:
http://www.zotero.org/
William