I'm not a single sourcer kinda gal - So, all over the place:
* social networks (twitter, facebook, g+, diaspora, etc.)
* discussion networks (stack overflow, disqus, quora, reddit, etc.)
* publications (usually through deepdyve or open access - varied and sundry - economist, techcrunchy, etc.)
* peer reviewed papers (usually through deepdyve or open access - often initially found through pubmed or Google Scholar)
* friends (lucky enough to have a lot of geekly friends who bequeath copious links and off the wall thoughts unto me ; - ))
I like to make a point of regularly reviewing new entries to the pool of options - I'm not ready to recommend any of them particularly, as they are still newbies, but this past year has seen copious growth in alternatives to all of the above (except for friends ; - )) - many with an improved focus on decentralization, peer reviewing options, and people controlling their own data - and has been particularly exciting from that perspective!