They include TweakVI (http://www.totalidea.com/) , TweakVista (www.tweakvista.com/tweakvistautility), and VistaBootPRO (http://www.vistabootpro.org/). And don't forget about Windows ReadyBoost, which lets you use a removable flash memory drive to boost system memory.
Are you using any of these apps or Ready Boost on your Vista Machine? Let us know in the comments!