Google+ makes it really easy to share your non-internet-related contact information with the people who should be able to see it. In light of that, remember to fill out your phone number and street address so the right people can get in touch with you (and maybe surprise you)!
Sometimes when I'm travelling, I like to send postcards to friends and family. However, I rarely know their street addresses. If everyone updated their G+ profile to share their address with those they trust, a few folks would have some surprise post cards waiting (at least from me :) )!
To fill out your contact information:
1. Click Edit Profile on your profile
2. Click the Home section
3. Add contact details
4. Choose Custom for your sharing option and select your circle and/or individual people