"OAIster is a union catalog of millions of records that represent open access resources. This catalog was built through harvesting from open access collections worldwide using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH)."
"OATD.org aims to be the best possible resource for finding open access graduate theses and dissertations published around the world. Metadata (information about the theses) comes from over 1100 colleges, universities, and research institutions. OATD currently indexes 5,218,230 theses and dissertations."
The ETD Center is a free, online database of Ohio's undergraduate, masters and doctoral theses and dissertations from participating OhioLINK member schools. It contains the abstract for all included theses and dissertations. The full-text is also available if it was submitted. (OhioLINK is similar to Minitex in scope)