[dmm]

I don't know about fighters, but ramming ships are effective in the early game, if you've got armor and repair. (Contrary to popular belief, rammers are not necessarily suicide ships, and can be reused indefinitely if you repair them.) And even if you don't normally use ramming, if your ships are way outgunned, then by all means use ramming. At least you'll take some of the enemy with you. But you must use tactical combat -- the AI doesn't look far enough ahead to see the benefit.

A strategy hint: once you've got armor III and repair III, research boarding parties. Now you can turn all of those heavily armored rammers into boarders. This can be done very quickly, long before anyone has self-destruct or "antiboarding" (I forget the official term) on their ships. Then analyze your stolen ships for quick tech boosts. (This is a REALLY cost-effective way to get colonization techs, and you don't have to trade yours away to a competitor.)