The Android's Dream (John Scalzi)

A complicated and fun SF story about aliens who are maneuvering for control over their own government and Earth as well, aided by humans who want to rule the planet as their governors. All that stands in their way is a resourceful ex-military diplomat, a pet shop owner, a few honest diplomats, an odd religion, and a sentient computer (or maybe two). A droll, tongue-in-cheek style smooths out the twists and turns, making the whole journey very enjoyable.