Meaning: God is Gracious Origin: English
A common diminutive for John, is Jack, which is quite popular at the minute.
John is known for being the author of the fourth gospel of the Bible, he is a saint in many Christian religions, being the patron saint of Hospitals and the ill, his symbol is the eagle.
Minimalist version Jon is also a nice choice (being Swedish, Danish and Norwegian). Slavic forms Ivan and Ivo have a contemporary feel as well. English (specifically Georgian) Vano fits in especially well with modern favorites Leo, Milo, Arlo and Hugo.
The Welsh name Evan is also a variation of this old-school gem.