Windows only: Free system profiler WinAudit is similar in some ways to the previously mentioned System Information for Windows, being a no-install-needed executable and offering exhaustive amounts of data on your system. What differentiates it are the graphed views of statistics like drive usage and installed software types, its easier-to-grasp interface (in one reviewer's opinion, anyways), and the fact that it doesn't reveal browser passwords, system keys, or other data you wouldn't want to accidentally sent to IT or a helpful friend. You choose the areas of your system you want profiled in the options, run the check, then print, save, or email the results. Helpful for anyone upgrading, troubleshooting, or even donating a PC, WinAudit is a free download for all Windows systems (seriously, back to even Windows 3.1).