But, as Dangermouse seemed to recognize, the alleged illegality of his music only helped to garner attention. Fan sites even hosted a "Grey Tuesday," during which they put the whole album online for free download. With his talents on full display, Dangermouse went on to greater and more mainstream success, even appearing on the Grammys earlier this year.
Mash-ups may soon be domesticated as well. The first fully licensed, industry legit mash-up album came out in the United Kingdom last month.
DJs are realizing that the copyright laws may actually help their cause. Sophisticated mash-ups that rise to the level of genuinely new art may actually fall into an exception to the usual licensing rules.
Under the fair use exception to copyright law, artists can use someone else's work for free if they fully transform it into something new. It's a high bar to meet this standard of "transformative," rather than merely "derivative" use, but it looks like DJs may be willing to try.
Additionally, courts dealing with copyright suits look at the economic effects of copying: If the unlicensed use wouldn't possibly hurt the market for the original, it's more likely to be deemed as fair use.
And this brings us back to Gillis and his DJ alter ego, Girl Talk, who has thus far evaded legal worries. Though he could not discuss the legal nature of his music, Gillis said the entire concept of a mash-up, or sampling, created a lot of gray areas in terms of art and originality.
"A lot of people are starting to integrate samples with original instrumentation. If you take a track and rearrange the notes, is that a mash-up or are you sampling?" he asked. "'Sampling' is such a vague term, and mash-up is an almost an unfortunate term because it confuses the issue."
Even if the perception of illegality and sticking it to industry giants (labels and artists) is an important part of the mash-up appeal, it also appears that Girl Talk has some friends in high places -- like Capitol Hill. His rabid success drove Rep. Mike Doyle, D-Pa., to testify that music licensing in an age of mash-ups has to evolve.
As a DJ, I can tell you that audiences are far from tired of mash-ups and a simpler system of permissions would only help the genre. But I wonder whether mash-ups will lose some of their edge once the law -- and the industry -- let them be.
ABC News Contributor Michael Smith provides a variety of DJ and music services to a number of International Brands and Customers. To hear some mash-ups he has recently worked on, check out www.smitheventmusic.com/listen.html and click on the Party Music stream.