OS X has a built in mouse acceleration curve which most people get accustomed to; however, in some instances having acceleration for mouse input can be frustrating. There are several tools and utilities available for managing the acceleration curve in OS X, which can help you customize how your mouse behaves globally as well as for specific applications.
If you use a third-party mouse, many times the manufacturer's driver will contain advanced settings that will allow for customization or elimination of the acceleration curve. Therefore, first try installing the drivers that came with your mouse, either from the included CD or from the manufacturer's website.
Use a universal driver
There are several universal drivers and utilities for customizing mouse input, which can handle the acceleration curve. Regardless of the mouse you are using, be it one from Apple or a third-party, these utilities should work for your mouse.
This is a utility that has been around since Apple started using USB in their computers. The program allows for customization of most mouse types, and can do so on a per-application basis. The utility has just recently been updated to work in Snow Leopard, and is also available for previous versions of OS X.
This is an alternative to USB Overdrive. While it was built mainly to customize Apple's mighty mouse, it does work with other mice albeit limitedly with some models.
This utility is an old one that was used in OS X 10.3 and 10.4 to adjust the acceleration curves for the built-in mouse drivers in those operating systems, rather than supplying a new driver of it's own. If you are using one of these versions of OS X, this utility should be useful; however, it has not been updated since the release of OS X 10.5 and 10.6.
Given it's versatility, I recommend people try USB Overdrive. The latest version has an interface revision that some long-term users have found confusing, but it is intuitive enough to get configured. The program is shareware but does not expire so you can use it as long as you like. The $20 registration fee will remove the information windows that pop up at boot and when you try to configure your mouse.