[AgentZero]

The mod I play with makes fighters quite a bit more useful, since only PD weapons can hit them.
In the stock game though, I usually used them as for planetary defence. After a planet had completed its facility construction, if I didn't need it to do anything else, I'd give it repeat orders to build one turn's worth of fighters. 10-15 turns down the line, if an 'undefended' planet was attacked, the attackers usually got a pretty nasty surprise.