The clove hitch is a great knot to know, no doubt. However, they're dangerous if the line to whatever you're tying up alternates between slack and tension, because clove hitches easily fall open.

In other words, if you're hanging a brace of rabbits from a tree branch, a clove hitch works great. Don't use one to moor your boat, though.

Gorgonzola suggests that if you follow a clove hitch with a couple of half hitches, your boat is safe. I still think a bowline is simpler.