Wow thanks. I really need to understand how lerp works.
I had to tweak it a little bit but I got it to work.
For future reference, my code now is this:
lerp(Camera.X, ((Player.X + Player.X + Mouse.X)/3), 12*dt)
This will make the camera focus on a point between the mouse and the player in a smooth fashion, kind of like looking around with the mouse.
This part "((Player.X + Player.X + Mouse.X)/3)" is basically averaging the distance between the player and the mouse, except its adding the player twice, so the average position ends up being closer to the player.