Here are some examples of Islandora and Hydra repositories, with a few suggested searches.
Please feel free to add more examples and comments!
McMaster University Library Digital Archive (search for Bertrand Russell)
Davidson College Archives and Special Collections (search for snakes)
See the list of Islandora installations for more.
London School of Economics Digital Library (see Public Lecture Series for streaming audio).
Oregon Digital (search for daily emerald spring break)
University of Virginia:
- Libra (search for violence and peace)
- Virgo (same search, view catalog results, limit to source Libra Repository)
Hydra is built on Blacklight. See http://projectblacklight.org/ for examples.