Kick your parties up a notch with the new Pacemaker DJ app ($free) for the Apple iPad. Pacemaker connects to both Spotify and your iTunes library, giving you access to millions of songs to choose from. Once you’ve picked your favorite tracks, Pacemaker gives you access to numerous DJ controls, including reverb, looping, beat skip, echo, a hi-lo filter and a roll effect. Another equally cool feature is automatic beat syncing, giving you the ability to instantly sync tempo and phase of two different tracks by tapping the SYNC button. Some of the features are free, some you have to pay for, but if you’re looking to switch up some of your favorite songs, Pacemaker’s a super fun way to get started. You can download it directly at the App Store.