I was looking for the exact same thing, and ended up going with the "Newest Generation Slim Capacitive Stylus" by A Young Life (AYL). Got it off Amazon, but it might be available elsewhere as well. Works great, slides with minor resistance, and has a much narrower tip than other pens I've used.
While point width doesn't make much of a technical difference, it certainly affects usability. All capacitive stylus models I've seen use a round tip, and the point of contact at the bottom of that little semispherical nub is what registers as a touch on the screen. No matter the size, a sphere is going to converge to a single contact point (with a little give due to material and pressure). But, since you can't see through the pen, you have to estimate the center of the nub when touching it to the screen. The smaller the blind spot created by the nub, the smaller the margin of error.