Books have been great, the more difficult the more nutritious. But the more nutritious they are, the harder they are to digest, so I don't recommend trying to read too many at a time.
Books themselves are also a great resource to find other great resources. Generally things that attract your attraction are the ones which give the best ROI. Books are a great place to find this, as you can trace a source and really consume it. Books like Tools of Titans are better off as a directory for discovery rather than read end to end.
Classics are worth reading when you find yourself pacing over an idea a few times. Discussing a lot of capitalism? Pick up The Wealth of Nations sometimes. Need help getting into the flow? Read the original book on Flow, by Mihaly Csikszentmihalyi.
I do want something that highlights good new tools and trends. Product Hunt feels a little too sponsored. HN is great, with good critical feedback, but it's biased towards the older crowd.
Facebook has been the source for 80% of my discoveries, but it's got a terrible signal-noise ratio. Only about 5% of FB is actually useful. But it gives a lot of anecdotal information about the rest of the world around me. I'd love to quit FB if possible though. A big part of my frustration with it is that dangerous misinformation is so abundant and spreads more easily than actual information. I don't see myself using FB actively in the next 5 years.
Reddit is fun, but I picked up nothing useful from my time there.
Browsing foreign job ads is a good way to see what's going on in the rest of world, and where the trends are flowing. There's a tendency for people to cargo cult tech that's just popular in their area, but this is a good way of seeing patterns.