I just found this online and I thought I would pass it on. The Missouri Death Certificate Database, containing death records created after 1910 and over 50 years old, makes that information available online through a searchable index that links to a digitized image of the original death certificate. The index can be searched by first name and last name, county, and by year and month. Once a name is selected, a digitized image of the original certificate can be retrieved. This is an ongoing project and additional records will be added as they are transcribed and imaged.
I have added a link to this valuable Missouri resource on my Death Records page on Ancestors At Rest.