I found this tough to answer, because self-directed learners tend to need different things, and are engaged in self-directed study for different reasons--while it might be a learning preference for some, for others it's a necessity for a variety of access issues. Not to forget that some learners might be very self-directed in some areas (eg. language learning) but require instructor-lead hand holding for others (eg. math).
I'm currently using OERs to learn statistics (a personal project over here http://oerproject.wordpress.com) and the most useful OER I've found is one I'd classify as "instructor-lead". It's a resource that's part of the open textbook project, and while it's appropriate for self-directed learners the most useful part for me has been the talking-head instructor videos explaining the content of each chapter of the book. However, it certainly goes beyond the repackaged course outline/reading list/set of powerpoints content that are clearly of limited use to self-directed learners.