Not sure on the accuracy of these, but I needed this info, found it, and wanted somewhere to stick it.

File Ext: Content Type:
docm application/vnd.ms-word.document.macroEnabled.12
docx application/vnd.openxmlformats-officedocument.wordprocessingml.document
dotm application/vnd.ms-word.template.macroEnabled.12
dotx application/vnd.openxmlformats-officedocument.wordprocessingml.template
ppsm application/vnd.ms-powerpoint.slideshow.macroEnabled.12
ppsx application/vnd.openxmlformats-officedocument.presentationml.slideshow
pptm application/vnd.ms-powerpoint.presentation.macroEnabled.12
pptx application/vnd.openxmlformats-officedocument.presentationml.presentation
xlsb application/vnd.ms-excel.sheet.binary.macroEnabled.12
xlsm application/vnd.ms-excel.sheet.macroEnabled.12
xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
xps application/vnd.ms-xpsdocument
by dmahugh

Thanks to:
Doug mahugh, on msdn blog