I've got 2 colony ships that are useless. The other races snagged 2 sweet planets I was heading for, which left the number of viable planets to colonize to zero. I plan to take them over with culture starbase spam, but what can I do with these colony ships? I'd like to reclaim that valuable 6 pop.
Another solution is, if you're at war with that race (or going to declare war), bring them back to your space (area of influence) then upgrade them to transports (if able) population will stay on the ship and now be troops. Now you can return to those planets and conquer them 