The ring is pretty much all powerful. It will do what you expect (or want) it to. Gollum wanted to be invisible, the ring did that for him. Bilbo got it from gollum, and frodo got it from Bilbo. Both Bilbo and Frodo kinda had the invisible thing on their minds when they used the ring, for obvious reasons.
They could have mastered the ring completely, if they were strong enough, and instead of a dark lord, you would have a SHORT dark lord!