So after toying a little with the game itself and biggest mods available here and there I feel like the "weel of ideas" is a little empty. All the units added are just big-bad-guns and nothing more. They add variety but they don't add fresh concepts (maybe except 4DC and it's unique race abilities but this doesn't work so far anyway).
My idea is to expand every faction roster with support type units (units that provide some kind of buffs/debuffs but don't deal any damage on their own), for example:
- Stationary targeting computer and mobile targeting comoputer (enhances accuracy/damage of friendly units/buildings in a small area around it),
- Nanobots Cloud (kind of a mobile engineering station that heals small amount of hp in small area around them),
- Stationary navigation computer and mobile navigation computer (enhances speed of friendly units in a small area around it),
- Weather Control Center (big building that allows to create fog/rain/blizzard in a small targeted area - nuke-like ability, which reduces visibility range and accuracy in target area but deals no damage),