What it does: Predictive schedules for subways and buses
If you don't have a car, firstly, God bless and good luck. Secondly, you're going to be using Metro's official app, which updates bus and subway schedules in real time and allows you to map out trips around the city/stun your friends when you actually get somewhere on time.
What it does: Maps out available/open parking throughout the city
Looking for an open spot is frus-tra-ting, but ParkMe takes a bunch of the guesswork out, working with the city (and Xerox, for some reason) to map out street parking and lot parking as it becomes available.
Free; premium version 99 cents
What it does: Deciphers horrible street signs
Once you've found your spot, the next thing is to know whether you're gonna get ANOTHER GODDAMNED TICKET if you park there; Park Safe LA will actually help you decipher the multitude of signs and curbs that seem to disagree with each other.