A company here makes a line of canned sparkling waters that are flavored with about a tablespoon of fruit juice. No sugar, no artificial flavors, no calories. They're not sweet, but that tablespoon of juice gives it just enough of a kick to taste like something more than water.
Of course, you could make the same thing yourself (with sparking water and a tablespoon of fruit juice!), and probably save money along the way. But I buy the cans.
I drink about three cans on a weekend day and about one every week night.
At work, I drink green tea.