This has been driving me nuts for a while now. The scroll wheel on my desktop mouse (it's an MS wireless optical mouse model 1008) scrolls rather fast. Instead of moving a few lines, it scrolls half a page or more with a very gentle scroll. The bluetooth mouse I use with my laptop does not do this so it's probably somewhat hardware specific. However, I'm wondering if there is a way to modify the speed or sensitivity. I found an answer here from about a year ago (https://answers.launchpad.net/ubuntu/+question/1339) that suggests there isn't a way but I'm wondering if anything has changed since then. I've also skimmed through synaptic but didn't see anything promising (like gsynaptic for touchpads).
See https://answers.launchpad.net/ubuntu/+question/9200 for more information.