Multitasking - the new way to exercise your brain?

We all know reading and doing crossword puzzles has been "shown" to help your brain. However, nowadays most people read online while watching television and/or listening to music (see: me right now, for example!) Besides the fact that the internet, text messaging, et cetera, is destroying proper grammar and spelling, do you feel tabbed browsing and multitasking is helping or hurting our minds?