The Mac is not the most competitive market for DJ-ing software (compared to Windows) but if it were, DJ-1800 would be one of it's best picks.
DJ-1800 is a complete, self-contained professional DJ system for the Mac which simply requires a decent AMP to get the most out of it. There's absolutely no need for a mixer, CD player or record deck and it can run from a digital music collection so there's no need to lug around heavy boxes if you're a professional DJ.
DJ-1800 can use a variety of MP3 and musical input sources so you'll never find yourself short of music options. If you've run out of space on your Mac for example, DJ-1800 provides support for music stored on an iPhone or iPod Touch. For professionals, DJ-1800 now supports all the major controllers including including the Denon DN-HC4500, M-Audio X-Session Pro, Numark DMC2, Numark iCDX and Numark Total Control For beginners DJ-1800 is a minefield - it''s incredibly complex to use but professionals will find DJ-1800 one of the most slick DJ'ing apps they've seen on the Mac in a while.