Select up to 3 answers.
I wonder if, instead of saying "reading the print journals" as an answer choice, you might say "reading journals in print or online" - I usually don't print what I download when I'm browsing a journal to which my library has an online subscription.
You might also say something about using an academic library's databases and other search tools like Academic Search Complete or the library catalog - these are mostly online and available wherever you log in with your academic credentials.
I wonder if, while academics happen to hear about research through social connections (whether online, in person, etc.), they might use academic libraries (mostly through libraries' online subscriptions, not by going to the building) when they are actually looking for research.
I'm amazed at how much I've been finding out about through Twitter! Usually, it is not something published in an academic journal, but rather some new idea, trend, video, or something else that's highly relevant to the work I'm doing.
The other way I find out about stuff that I don't see listed on your poll is making visits to schools to give presentations and then spending time talking with people one-on-one about their work. I'm always surprised at how much stuff I find out about that I didn't know beforehand. This past fall semester, this has involved visits to Ann Arbor, Boston, Ithaca, Atlanta, and Chicago.