It's always a good idea to use caution whenever you're playing with raw garlic — a little bit goes a long way. Adding a few drops of olive oil can help mellow the garlic to some extent. Other variations include substituting fresh mint for the parsley, or adding a few minced capers. The capers are especially nice if you're serving the gremolata with salmon.
Gremolata is an easy way to add an elegant touch to a dish, and it does double duty as both a condiment and a garnish. Check out this simple gremolata recipe.