Respondus StudyMate Class is a web-based authoring tool that makes it easy to create flashcards, puzzles and simple games for D2L. It allows students to add content, too. StudyMate Author does the same but is Windows-based. The links below will provide more information about each program.
StudyMate Class - web-based activity generator
StudyMate Author - Windows-based activity generator
Publishing to the D2L LMS is not an option so you must choose "Publish to StudyMate.com" or "Export as a learning Object (Flash, SCORM) for manual upload" to export and use your StudyMate objects in D2L.