The Bitcoin Core developers have a desire to do a mostly bug-fix, cleanup and translation update release in v0.9.2 a few weeks from now.  You do not need to be a developer to help!  With these unofficial nightly builds, power users can more easily aid in testing of the master branch which will help to find bugs and polish things up faster.  Additionally translators can more easily run the latest code and see what strings need to be translated as we rapidly approach the next stable release.

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Warren Togami