Idea - Coordinated Assault / Negotiations
I've read a handful of comments regarding the sometimes slow pace of gameplay towards the end of a sector. The ability to coordinate attacks with an ally against mutual enemies via the trade/negotiations menu would be both awesomely fun and help to accelerate near-end-of-sector-gameplay.
Attacking enemy planets alone can be quite a challenge, often deadly. Negotiate: coordinated attack against planet X (race). This could go in a number of directions. "Before we launch an assault, we need to set up a base at Y.", etc. Once an assault is initiated, your allies will send ships to attack target planet. You can join them in the attack.