I searched the boards for this suggestion and didn't find it, so I thought I'd post. I am a micromanager, and I am constantly tweaking my colonies in the civilization manager. I love how the "planet class" column shows the number of useable tiles and notes the number of open tiles in parentheses.

I would suggest a similar mechanic for the population column. Current population (max population). Alternately, the number could be color coded, yellow for a planet at max population and green for a planet with room to grow. This way I don't have to scan the list for planets at 5.0, 9.0, 10.0, 11.0, etc and click to see if I need to build a farm or not.