There's no substitute for up-close viewing of original works, but Google's offering a virtual tour, and close-up zooms, on art in the Met, Versailles, the Van Gogh, and other world art destinations with a free site powered by Street View.
The click-to-walk tours themselves are pretty nice, and a great way to explore far-off museums and relive your memories of your own visits. But on many works, you can click to get a zoom handle, and the detail goes right down to the paintbrush hair strokes. So give yourself a break from YouTube on your lunch break and take a free stroll around some major institutions.