Middle finger.
I also have a scroll button on my touch-pad. However, I rarely use either. I’m so used to using the arrows keys for scrolling that using a mouse wheel doesn’t feel right to me
It suddenly occurs to me that my mouse is poorly designed as are most mice I have used. Middle finger would be logical. But if I hold the mouse in a coufortable position the scroll whell lies just below the knuckle on the middle finger. It needs to be a whole lot further forward.
I scroll with my middle finger. That way, my index finger is poised and ready to go on the clicker!
My arrangement of fingers is thusly:
Thumb: on side thumb button
Index finger: on left button
Middle finger: on scroll wheel/button
Ring finger: right button
Pinky: anchoring the mouse on the side. (There’s a small indentation there, perfect for my little finger.)
(I use an iFeel Mouseman by Logitech: found it at a BigLots! for $10. Best $10 I’ve spent on computer-related stuff.)
<< No one is listening until you fart. >>
Depending on my mood, it’s my ring finger (most of the time) or my middle finger; only very rarely do I use my index finger for scrolling.
Actually I think it’s time to get off the computer now. My ring finger is starting to ache from the scrolling.
I’ve always used my middle finger to scroll. I keep my index finger on the left click so I can click stuff and not have to switch fingers.
I always use my index finger… Probably just because it was natural for me to do that, but I also right-click a lot… not as much as I left-click, mind you…but enough that it would be equally as ‘annoying’ to switch fingers around.
The reason I right-click more than I think the average computer user is that I don’t surf the web w/just one window. I’ll open up one and then open new pages in different windows…my connection is terrible and I have enough RAM that it works out…
Wow. I feel strange now.
I left click with my index finger and use my middle finger for scrolling and right clicking.
Perfect for Unreal Tournament.
Scroll-wheel with the index finger, right click with the middle. Unless I’m using a Sun style 3 button mouse like I do at work then it’s Index, Middle, Ring, across the buttons.
Middle Finger
My most used finger 
Left-click and scroll with index finger, right-click with middle finger. Logitech builds their mice too damn small, it’s descriminatory and I’m contemplating a class-action suit against them.
Middle finger. I use a scroll wheel mouse at the office, and when I get home I find myself stroking my (wheel-less) Apple mouse in an odd manner while surfing.
I use my middle finger. It’s had more practice at the up and down motion.
The Bird
Declan
Index finger to left click and scroll, middle finger to right click.
Though it does make more sense to use index for left, middle to scroll, ring to right click. I’m wondering if more men do it this way, while women use their index?
Middle finger. Unless I’m smoking, in which case I use my ring finger, as my middle and index fingers are involved in holding the cigarette.
Mouses (mice?) with no scroll wheel drive me nuts. My boyfriend’s mouse has one, and my mouse at work has one, but mine at home does not, and I’m constantly trying to use it and failing.
left click with index
wheel and right click with middle
it’s that simple
im another for both and computers without scroll wheels do annoy me, especially when you are expecting a scroll wheel and roll to find nothing is happening, the other great thing about scroll wheels is the “Open Link in New Tab” usage with Firefox
The only thing worse than a mouse without a scroll wheel is a browser that doesn’t make use of it.
Mozilla, I’m looking at you.
Middle. Always.