One of the most famous collections/frameworks for development and usage of (traditional) machine learning algorithms is weka [1]. It is written in java, and actively developed by the machine learning group of the University of Waikato. They also seem to have a forum to discuss, which should be a good resource given that a lot of their users are actually researchers.
The very same group is also developing another framework (also in java), MOA [2], that is oriented towards "big data": the algorithms used in there are specifically tailored for huge datasets and/or realtime (streaming) machine learning.
The very same group is also developing another framework (also in java), MOA [2], that is oriented towards "big data": the algorithms used in there are specifically tailored for huge datasets and/or realtime (streaming) machine learning.
[1] http://www.cs.waikato.ac.nz/ml/weka/
[2] http://moa.cs.waikato.ac.nz/