I have been using the Superfine Liner for Brows now for about 4 years, and never had any urge to look for something else in the meantime, a definite first for me!
As the nib on this is very fine you can easily achieve the look that you want. I tend to go for quite a natural look for every day, but you can easily build it up if you want something a bit more bold.
The Clinique Superfine Liner comes in 4 shades; Soft Blonde, Soft Brown, Deep Brown and Black/Brown. They are £13 each but they do last a long time, and I wear mine every day. I would say a good 6 months worth in each pencil.
On the next picture I have only drawn one eyebrow on for comparison:
What do you use to give your eyebrows some life?
Here we have Karl messing about: