As noted in our 20 best new features in OS X 10.6 Snow Leopard article, Snow Leopard is packed full of other refinements. The revised Keyboard preferences bring order to what was previously a mess, cleaning up and making Services useful to boot. Services are now contextual, only appearing when relevant, and they can be toggled via checkboxes.
System-wide text replacement reminiscent of OS X for iPhone is built into the system, ready for app developers to take advantage. Usefully, Apple enables you to define your own substitutions via the Language & Text preferences. In another nod to the iPhone, Core Location enables your Mac to figure out where you are, without you having to manually change your time zone.
REFINEMENTS: System-wide text replacement joins Mac OS X's existing spelling tools
For Mac users regularly sharing content, the new wake-on-demand feature should also appeal. It enables supported Macs to activate on request from another network device (for example, for iTunes library sharing or printer sharing). However, this requires an AirPort Base Station or Time Capsule to broadcast Bonjour messages about services offered by the sleeping Mac.