Okay.... I've only used this trick a couple of times, and it's kind of ... well... *DANGEROUS*... but you can come off looking like the KING OF DJs if you pull it off.
One night I was playing at a smaller club and one of the decks was giving me problems with feedback. I had to keep nudging the gain down to keep that annoying whine from creeping up. The situation pissed me off so much that my set was terrible, and at the end I just thought "Ahhhh.. fuck it. Let's at least give them something to remember!" So I cranked the gain, locked the arm, and lifted up the deck trying to get some neat sounds while my last record finished out on the other deck. If any of you play electric guitar, or have seen any old Hendrix footage, you know what I'm talking about. Well, fuck me sideways, BUT IT WORKED! It's pretty much just like an electric guitar. The distance and angle of the deck in relation to the monitor will generate different harmonic overtones and result in varying feedback notes. The thing that is really funny is that the feedback was actually in the same key as te sounding record (which will not always be the case). And even though my set blew due to my frustration, the crowd loved it simply because of the flashy ending!
Obviously, this is not something that you can always pull off, or something that you would want to overdo. But it IS something that will get people talking about you. It is even possible to play simple melodies once you get a feel for it.
Anyways... try it out. It's up to you to decide if it falls on the "stupid" or "clever" side of the line.