Here are some great genealogy resources for Iowa:
FamilySearch Research Wiki – Iowa
Historic Archives Digital Collections
Iowa Online Genealogy Records at FamilySearch Wiki
IA GenWeb – Site organized by counties and run by volunteers. Free and well worth a visit as some unique items are sometimes found.
Burlington Public Library – Genealogy
Davenport Public Library – Genealogy & Local History
GenWed – Free Iowa marriage records online
Iowa Heritage Digital Collections
Iowa Historical Newspapers Digitized – University of Northern Iowa Collection
Iowa State University Digital Collections
Linkpendium – Iowa, with thousands of links to resources in every county
New Horizons Genealogy – Free Iowa records
Online Iowa Death Records & Indexes
RAOGK – Iowa Archives, Historical & Genealogical Societies – Many links to groups in Iowa
The Daily Iowan: Archive Covering 1868 – Present
University of Iowa Libraries – Special Collections
University of Northern Iowa Digital Collections
Societies
Des Moines County Genealogical Society