Institute for Scientific Information (ISI)
The ISI currently captures DOIs in their records. However, the DOI is recorded at the same time as the volume/issue/page number. Therefore, it is not using the DOI to capture information prior to print publication, but rather recording it simply as an additional piece of metadata to complete their records.
Medline currently captures DOIs with online publication dates in its records, and is developing an enhanced level of support for the DOI system.