I've gotten some questions about using Office SharePoint Server 2007 to crawl websites that use Forms-based Authentication (FBA) or Cookie-based Authentication (CBA). SharePoint Server 2007 supports this functionality with a hotfix. (If you don't have the hotfix installed, only the logon page will be crawled.)
You can download the hotfix here: http://www.microsoft.com/downloads/details.aspx?FamilyId=B3C932A5-B3C0-4473-8EA5-62AE44190878&displaylang=en
Before you install the hotfix, be sure to review this KB article: http://support.microsoft.com/kb/934577/en-us