Spin the Beats on the Cheap (click to embiggen)
There are two camps in the world of DJing--analog purists and the cutting edge digital folks. While the purists will hold on to their vinyl like a child clutching its favorite toy, the digital folks are out there looking for the best way to rock the house while attempting to stay out of the poor house. With all the software and hardware aimed at digital DJs, it's easy to get fooled into thinking you need a few thousand dollars in equipment to bring the noise. The latest update to djay by Algoriddim will give you the power to rock the beats without breaking the bank.
For the beginner, djay is a painless entry into the world of DJing. For veterans, it's a wonderful addition to your arsenal that doesn't skimp on features. For $50, you're given a surprisingly powerful piece of software. Djay interacts with your existing iTunes library, offering instant access to any DRM-free music you have on your machine. The interface looks like a typical DJ setup with two turntables and a mixer. Drag songs from the music library in the app onto the turntables and they become virtual records complete with album art (if available) while the track name appears above the album with the time elapsed and time left. Helpful if you're in a dark room trying to figure out what song is on each virtual deck.
Fans of multi-touch will appreciate the quick gestures to fade between songs and the digital scratching. While virtual scratching has a ways to go before it replaces the feel and control of scratching a vinyl record, djay does a commendable job recreating the feeling via multi-touch on the track pad. As tracks are added to the mix, the app quickly displays the BPM to help you determine whether the song will work in the mix, or if you need to speed up, or slow down the track for a seamless mix. The Sync button will help match the BPMs of the two songs, or you can adjust it manually. 
The new audio engine handles scratches, variable speed, and reverse admirably even going so far as to replicate the braking sound of a turntable that has been stopped while the needle is still in a groove. The smooth slow-down of the song will spark memories in those of us old enough to remember vinyl. The software ships with audio effects and an EQ to get the sound just right.
If you're tired of mixing and need a break, you can use the Automix feature, build a playlist and let the application take care of the mixes while you cruise the party.
Djay 3 will be available from algoriddim on September 29.
For new and old DJs, djay is a feature-packed application that'll keep the party bumping—all for a fraction of the price of less-capable DJ packages.
Incredibly robust application. Fun at parties without busting your back carrying equipment up four flights of stairs. 
Purists may scoff at you. 
nightshrill
September 26, 2009 at 2:21am
There are multiple problems that occur when dealing with programs like this for DJ'ing. Granted if you're doing video work this is probably one of your best options format wise, however unless you are ripping w/a lossless codec such as FLAC then the cd holds a higher quality of sound, not only that but with a computer program you are unable to control multiple things at once, for example rather than relying on the crossfade option you can manipulate sound levels on both decks for a much better transition, or if you want to beat match while adjusting sound levels or anything else you need actual fingers and actual buttons because last time I checked there was no option for two independent mouse pointers on the screen (then the problem of coordinating them). Also, physical equipment is not nearly as expensive as you make it out to be, a starting DJ can pick up a Numark CD Mix 1 (or preferably 2 because its not that much more expensive and is higher quality) for $200-$300, a far cry from the thousands you stated. It also eliminates chances of computer issues overall such as CPU slowdown (these programs love to eat cpu), while the physical equipment has its own processing units, etc. So although this may be a cheaper option compared to the 200-300 for a pretty standard mixer/dual-cd deck its very much worth it.
On a side note analog is subpar sound quality compared to digital recording methods, although I have quite a few vinyls that were never released on cd's I will not and do not bring them around with me because i trust no one else's player but mine (rare stuff).
