Here's a few things I've been involved with.
The .Astronomy conferences, led for 7 years by Oxford astronomer and TED Fellow Dr. Rob Simpson (now at Google), bring together scientists and educators to share ideas and collaborate on innovative computing projects for astronomy to leverage the immense potential of modern computers and the web. Over the years .Astronomy has created a growing community of astronomers who think and work creatively on new ways of exploiting the web for science, and as part of the conference we organised the first astronomy-themed hack days. I organised the 2009 and 2012 instalments of .Astronomy. In 2014 I hosted a software hack day at the SPIE conference on Astronomical Telescopes & Instrumentation in Montreal; I'll be helping to organise a similar event at the 2016 SPIE conference in Edinburgh.
The Zooniverse group, based in Oxford and Chicago and led by Dr. Chris Lintott, have created a suite of citizen science projects in areas from astrophysics to ancient Egyptian papyrology. I'm a member of the science team for the Milky Way Project, which aims to study star formation in the plane of our Galaxy using survey images from the Spitzer Space Telescope. By gathering data on the images from thousands of volunteers, we can perform statistical studies of galactic star formation, and use our volunteers' data to train machine learning algorithms. Citizen science provides a unique avenue for the research community to engage with thousands of keen enthusiasts around the world.