Athlon 64 overclocking tools
Some I've heard of, others I haven't...
ABXZone.com Forums - A64 overclocking tools. There are several utilities that make it much easier to overclock and tweak an A64 system.
"Clockgen":http://www.cpuid.com/clockgen.php - Allows you to change HTT (FSB), CPU multiplier and AGP/PCIe frequency in Windows. This works but you can crash your system very easily.
"A64 Tweaker":http://home.exetel.com.au/codered/A64Tweaker/A64Tweaker_V031.zip - A program written by Australian overclocker CodeRed. Allows you to change memory settings in Windows. There are also two beta versions: 0.5 and 0.6. CodeRed recommends using the first version (0.31).
"MemFreq 1.1":http://www.forumdeluxx.de/forum/attachment.php?attachmentid=7536 - Program written by German overclocker goddh0r. Will calculate your memory speed, depending on which divider you're using.