So much of what we do these days is electronic that it's easy to dismiss the rapidly-decreasing number of reference books lining the shelves. In some cases, though, you can spend hours searching the web for information, getting more and more frustrated with badly structured sites, when a quick check in a book would do the job.
My latest book discovery is our copy of British Parliamentary Election Results 1950-1973, edited by FWS Craig - it took me two minutes to copy out the result of the 1959 general election in Dumfriesshire, when I would have been lost on the parliamentary website. Sometimes the internet is quicker - Hansardis a good example (I don't know anyone who consults the paper version any more). But get to know your reference section too, books sometimes are better. And still on the subject, I noticed yesterday that the hardcopy of the 2006 Guinness Book of Records had a few entries that were more up-to-date than the website.