If you see people sneaking around a neglected lot, digging in the dirt, they may be guerrilla gardeners. Like using your cell phone to send city officials photos of potholes in the street, it’s another sign of the new wave of community-building and sharing.

Other fresh signs of sharing are sliver time volunteering, co-housing, book swaps, the Village Movement, free samples, car and ride sharing, co-creating house plans and local exchanges of free stuff.

Now there’s a whole online magazine dedicated to delights of the shareable life.

Trading is another approach to sharing. On your next vacation, save money and get to know another community when you trade homes with someone who lives there– and introduce each other to your neighbors and friends.

Relatedly, make extra money while helping others save it by renting what you already have. Think of your tools, office, parking or storage space, or even your couch.  And when you want something new, see if you can get it for less by getting others to buy one too.

Janelle Orsi and Emily Doskow describe other“sharing solutions” and Rachel Botsman and Roo Rogers dub this trend “collaborative consumption” in their book What’s Mine is Yours.

How have you saved or made money, forged friendships or helped your community by sharing, swapping, renting or otherwise acting collaboratively?