As many of you might know, the functionality of double directional syncronization between SharePoint lists and Excel sheets was removed in the 2007 version. Why? I don't know, it probably didn't make the magic features-that-will-be-included-line. However, an add-in for Excel 2007 can now be downloaded that enables this feature.
Check it out: http://www.microsoft.com/downloads/details.aspx?FamilyID=25836e52-1892-4e17-ac08-5df13cfc5295&DisplayLang=en
CRM and SharePoint Consultant