Free Exceler8 for Revit from Case: Roundtrip Revit Data to/from Excel (Updated)
"This is a must have utility that supports the export as well as import of data from Microsoft Excel 2010 and higher. While this tool is still under fierce development, it is ready to use for basic use. We have lots of features planned for this one that will make it into a series of future updates."
There's more information available on the Case Apps website.
Update 5/8/2016: CASE and the CASE Apps website are no more but, courtesy of WeWork, the CASE Apps are now open source. They may be accessed on GitHub.
David Light has been posting about how to use Exceler8 over on his Revit blog.