90 prelude clutch fluid missing out of master cyl from just sittin in driveway...no visible leaks ...replace master cyl? new hydro lines...

 

Sitting where? There 3 parts, a master cylinder on the firewall, slave clyinder on the tranny and hard and soft lines that's connect them. If the puddles on the passanger side, probably the soft line or the slave cylinder, if it's by the drivers side, it might be the MC.

Clean everything with a towel, fill and bleed it, most likely you'll see where it's leaking out. For a car that's now 19 years old, it might be worth considering replacing all 3 if your worried about it stranding you.