Venture capitalists have invested hundreds of millions of dollars in scooters — electric scooters, specifically. On a sunny day in San Francisco, they're clogging every sidewalk. Lime and Bird are the two best-known options. They also operate in Santa Monica, California; Washington, D.C.; Austin, Texas; and Atlanta. You use an app to check out a scooter, GPS tracks your location and you just drop it anywhere when you're done with it. There's speculation that Uber or Lyft will buy one of the bigger companies since both have invested in electric bikes. Bird is being valued at $2 billion.