At a presentation of beginning research, those attending seemed shocked and excited when I showed a slide of a death certificate. I had located the digital image of the death certificate on Internet. Naturally they became excited thinking that every state has death record images on Internet. They don't, but there is an abundance of information in those areas on Internet.
One of my favorite web pages is Joe Beine's Online Searchable Death Indexes, Records & Obituaries. This web page provides links by state plus big city guides for places such as New York City and Chicago. Missouri Digital Heritage does have death certificate indexes and images for 1910-1959 and that's where I found the death certificate I exhibited in my presentation.
Beine's web site contains many links to county records that have been indexed or transcribed. There are burials indexes, cemetery tombstone transcriptions, obituaries and indexes plus indexes to death certificates. A few states do provide digital images, such as Utah Death Certificate Index for 1904-1959.
The FamilySearch BETA contains death certificates, such as for Ohio. This is a great web page to explore if you realize that you must return consistently to catch up with new images, new indexing and projects.
Perhaps in time we will have many more states joining the Internet with digitized vital records. It will definitely be a great day for genealogists!