Somewhat off topic, but cool researchable technology idea:
It would be cool if the drop tanks on the phoenix could be replaced with bloodspider pods, which directly upon landing, released reprogrammed bloodspiders (maybe two or three per pod) that fight on your side. These would be in addition to your troops and would not affect troop count. The downside would be that they could not be built, only made from repaired bloodspiders that you have killed, and they would be under AI control, not player control.
Great for automatic scouting out enemies, but uncontrollable. Likely to be lost, as they'll not be as smart as a player and will likely rush into groups of aliens, and difficult to aquire, so you save them for those really hard missions.