Sounds like the timing belt. The belt can look good, and still make a noise, especially when the engine is cold. If it is the timing belt, it will probably quieten down after a few minutes, and not make the noise again until the next time you cold start the engine. When the noise occurs, place your hand on the timing belt cover, and see if you can feel the belt hitting the cover.
I believe various pulleys on the passenger end of the engine can also make a ticking noise, but I've never had this problem myself.