If you are one of the nine remaining people in the world who haven't signed up for Uber or Lyft ride services yet (There were only about 12 people left when I signed up, so don't feel bad.), here are a couple of reasons to do so: free credits.
I used my Lyft credits today, since they expire in a couple of days. I found the drivers to be a bit more interactive with Lyft than Uber and the prices a touch cheaper (no surge pricing during rush hour today, for instance). On the other hand, there are more Uber drivers and the app is a little more user-friendly. But on a the third hand, we each get the credits below if you sign up with my referral code. Nothing like a couple of free rides.
Lyft: MICHAEL918142 ($30)
Uber: michaelf1649 ($20)