DISCOVER searches now include two key open access sources: OAIster and arXiv.
OAIster (pronounced 'oyster') includes information from a huge number of institutional repositories and other databases that allow their information to be harvested through a standard called OAI-PMH. Most of the content in such sites is free but sometimes you will find content that you can't access and sometimes you will find broken links. Those are the fault of OAIster not DISCOVER! We have included OAIster in all our DISCOVER search profiles.
arXiv (pronounced 'archive' as if the 'X' were the Greek letter Chi χ) is the pre-prints service for physics, maths and computer science. We have included arXiv in the main DISCOVER profile and the one for Science and Engineering.
We have now expanded JSTOR's coverage in DISCOVER to also include the collections that we don't subscribe to. These lack the full-text links to JSTOR (we don't have access there, so what would be the point?) but they may help you to find articles that we have through publisher backfile purchases, or in hard copy in the library, or at least to allow you to try ordering them through ArticleReach.
Similarly we now include Informit content in DISCOVER. Informit covers journals from Australia, New Zealand and the Pacific and even though we don't subscribe to Informit we may have access elsewhere to some of the articles it hosts.
Finally, eBooks from Oxford Scholarhip Online are included in DISCOVER. Data and links are at the chapter level to give your searches more chance of finding relevant content.