Among them is the marketing department of Veritas Software in Mountain View, Calif., where e-mail with other on-site employees in the division has been banned on Fridays since the summer.
"You can be furiously e-mailing someone even as you're looking at the back of their head," said spokesman Andrew McCarthy.
Michael Parker, 40, marketing manager at Veritas said many people are unaware of how insidious e-mail has become.
"E-mail is like drug addiction. You say, 'I can stop anytime,' or 'I'll just send one more.' Then you're on for hours," Parker said.
RadioShack's new riverfront campus in Fort Worth has cubicles for employees. But to encourage more in-person conversation, common areas have wireless Internet access so employees can sit together and work.