If you are running an older Mac you may have noticed how despite upgrading to OS X 10.10 Yosemite you still don't have access to cool new features such as AirDrop Handoff, Instant Hotspot, collectively known as Continuity. These features are core to iOS 8, and so if you have a newish iPhone or iPad, and an older Mac, you could be missing out.
But with a little hardware upgrading and a free software patch, you can activate these features and add a few years of life to your system.
Enter the Continuity Activation Tool, the brainchild of David Dudok de Wit. This tool gives unsupported Macs access to these new Yosemite features. Depending on your Mac, you might be able to activate Continuity with no hardware upgrades required (if you have a 2011 MacBook Air of Mac mini, you are in luck), otherwise you may need a Bluetooth 4.0 USB dongle or new AirPort Extreme card.
It's worth pointing out that this is a hack, and as such things can go wrong, so make sure that you have a current backup of all your data.