There has been a strong trend over the years of using popular music to set photos to in a slide show. This recent article from ABC is about how a photographer is being sued for using music that is covered under the laws of copyright. Are you using popular music on your website or for making slide shows that you post online or give to your clients? This could be something that you might want to look into for your own protection!
The best way to look at this is how would you feel if someone just took your images to use to promote their music? You would probably want proper credit, to be paid or ask to have it taken down.
There are companies out there like Triple Scoop Music who do offer royalty free music for a small fee, but it is not popular music so many people are turned off by it. But think of the legal ramifications if you do choose to use copy written music. If the recording industry, ASCAP and BMI (royalty fee collection companies) decide to start going after people for not paying the usage fees this could get expensive! The best way to protect yourself is to use royalty free music, this doesn’t mean you have to buy music from a company like Triple Scoop, if you have any friends who are musicians you can always ask them if they have any music they would let you use. It might not be exactly what your clients want, but if your clients understand the legalities of it they might be a little more understanding.
If you are making a short film there is always mobygratis.com film music is for independent and non-profit filmmakers, film students, and anyone in need of free music for their independent, non-profit film, video, or short. Here is an example of a short film I made using music from the mobygratis.com site! Of course to use their music it has to be non-profit, and in my case I made this film just to add to part of film portfolio.