Previously, the research community has collaborated through various google groups / mailing lists. Some are still active:
Human Knowledge Compression Prize (HKCP)
https://groups.google.com/u/1/g/hutter-prize
Algorithmic Information Theory (AIT)
https://groups.google.com/g/ait0
Others remain (primarily) of historical interest:
Mathematical Artificial General Intelligence Consortium (MAGIC)
https://groups.google.com/u/1/g/magic-list
Universal Algorithmic Intelligence 