Whiners, complainers and gossipers
In my experience, people who complain about others at work are usually a worse employee than the person they are complaining about. When someone comes to you with a complaint about another employee, I recommend that you pull the people involved directly into the office so you can all three talk about it, there and then. Does it make people uncomfortable? Yes. But it meant enough to them to bring it to you, and they expect some sort of reaction. They got it. In the future, they will think hard before bringing the petty things your way. Make this your reputation as a leader, and you'll know in the future that if they do bring something to you, it is a valid complaint.
If they want to gossip about another employee, inform them that your next move is to tell that person what was said, and who said it. That will bring it all out there in the open. Your job is not to keep secrets. Your job is to prevent them. Not allowing gossip to happen in your presence, and letting your staff know the repercussions if they do, will help to eliminate the problem.
Awkward? Yes. And thus, only those with BIG complaints will come to you for a solution. It will squalsh most or all gossip that comes your way, and you can go on to focus on those bigger fish you have to fry.
