My computer often refuses to load the calculator so I even google maths stuff. Handy site really. That and spellings, words I don't understand and crossword clues.
I usually keep my phone nearby when I am reading a book, so I can look up references that I might not understand.
With crossword puzzles, the ground rules I set for myself are: first, try to hold out and figure out the word from the other words I fill in; second, limit myself to hunting through print reference books I have at home; third, if desperate, turn to google.