snowflakes and golden dwarf morays (though pricey) are generally considered reef safe eels. There are some others, but those are off the top of my head.
The thing about eels is that they're "reef safe" because they don't bother corals. They can, however, bother clams, snails, crabs, shrimp and sometimes even fish. I've had my snowflake for about 2 months and he has never touched anything in my reef.