L2 (Left Trigger) is very useful. When you want to go somewhere but your Sims isn't close, hold down L2, click a spot, and select "Teleport me there." The second use is to hold L2 and click a Sim to get three new interactions:
1. Add sim to family 2. Modify traits for active sim 3. Trigger age transaction.
Finally, if you hold L2 and click the mail box, and get a full cheat list.