Apple has released iMac SMC Firmware Update 1.1, which is recommended for recently released iMac models that have been configured with PCIe-based flash storage (see “Apple Updates iMac with Faster CPUs and 802.11ac Wi-Fi,” 24 September 2013). The release improves the Power Nap feature in OS X 10.9 Mavericks so that it runs silently while your iMac is sleeping without spinning the fan. (Free update, 921 KB)
Mac OS X Services in Snow Leopard
Mac OS X Services let one application supply its powers to another; for example, a Grab service helps TextEdit paste a screenshot into a document. Most users either don't know that Services exist, because they're in an obscure hierarchical menu (ApplicationName > Services), or they mostly don't use them because there are so many of them.
Snow Leopard makes it easier for the uninitiated to utilize this feature; only services appropriate to the current context appear. And in addition to the hierarchical menu, services are discoverable as custom contextual menu items - Control-click in a TextEdit document to access the Grab service, for instance.
In addition, the revamped Keyboard preference pane lets you manage services for the first time ever. You can enable and disable them, and even change their keyboard shortcuts.