Am I the only one who can't remember which technologies are in your tree? I could go for a second symbol in the diplomacy screen indicating which technologies you could/could not research on your own. Something like a '-' to indicate technologies that aren't unique to the race you're speaking with but don't appear in your tree.

I'm beginning to think some sort of filter for mine/alien planetary improvements might be nice too. While it's interesting to be able to build them, it does tend to get cluttered as you gain alien technologies.