This summer, I'm planning to travel around the Kanto area on JR's Tokyo Wide Pass. The pass is available to foreign residents (show your passport for this). The pass is valid for three consecutive days on JR East lines and half a dozen other lines in the Tokyo area. The advantage of the pass is that it allows you to hop off and could save you a bundle in train fare.
The three trips I want to take are within 2-3 hours of home, so I'll use the pass for day trips. Have you traveled on an economical train pass? Did you get good value from it?