They started out trying to build a decentralize wifi network using Helium Hotspots. Some people were making good money by setting up a hotspot at their home. You're rewarded with Helium (HNT) tokens when people use your hotspot.

Now they are also working on a wireless (phone) network. You can get Helium as your cell phone provider (they piggyback on the T-mobile network). It looks like it's only $20 a month though for phone service and they incentivize you to pay your bill in HNT. I'm thinking about doing it. I think your phone then acts as a Helium hotspot, but I might just be making that up.