When installed it allows you to call a number or send a text message just by right-clicking on the number in the Address Book (or selecting it elsewhere and invoking Phone plugins from the Services menu). It works with a number of phones from Motorola, Nokia, Samsung, and Sony Ericsson; check the compatibility list for details. Annoyingly the iPhone is not compatible.
Nova Media Phone plugins is $9.95 and a demo is available.
[via Hawk Wings]