Beside Vestax' Spin2, there is a new option if you like to control djay with external equipment: Pioneer DDJ-WeGO. The latter only controls djay on Mac though, while the Spin2 also works with iPhone, iPod and iPad.
Pioneer's official announcement
Pioneer's DDJ-WeGO DJ controller can now be used to control Algoriddim's djay software for Mac. Designed for home DJs, the Pioneer DDJ-WeGO is a compact portable DJ controller that is easy to set up and use anywhere. DDJ-WeGO is available in five different body colors to suit your preference and features a multicolored LED for customization of JOG light colors, which enables individualistic DJ performances by combining various lights and effects. The compact size and portability of the controller make it ideal for home DJs who want to enjoy DJ on the go.
DDJ-WeGO users can download and use Algoriddim's djay LE free of charge from Algoriddim's website. As we know, these controllers let us do much more than we really need as Swing DJs, so it's a fundamental decision if you would like to have an external controller or not.
What do you think about DDJ-WeGo?