There is a bunch to use. Any of the Adventure paths from Pathfinder work well and are easy to covert, so is most modules and dungeon crawls.
I would also suggest looking into settings and then kinda building your own meta plot around the setting such as;
Dark Sun
Ravenloft
Red Steel
Eberron
You can even have some generic plot line and throw in a bunch of mini dungeons until you get your groove. For example; bad guy is looking for items of power to take over the universe. As your players are trying to stop him or find the items before he does or whatever every town you enter can have a lil mini plot. Like this;
Town One: Dead won't stay dead, zombie invasion must help the town and find the source od the zombies.
Forest Path: Lost children, must find their parents or what happened to the caravan they were traveling with.
World of Warcraft quest: In town, something happens either someone you needed help from is poisoned and you most got find these items and those items etc.
Anyway, I hope this helps.