Miami-Dade County, Florida Recorder's Record Search
In order to search for only a death certificate you must select "Death Certificate" from the Document Type selections in the drop down list. This appears to hold records which have been digitized by the Miami-Dade County Government and made available to the public. The death certificates appear to cover the years of 1973/4 - 2002.
You may conduct a search for documents based on various criteria and view detailed information regarding any particular document.