If you have ever programmed orchestral concerts on a budget – regional music directors and education conductors know what I'm talking about – U.S. copyright law and its arcane ramifications have doubtless driven you to distraction. Want to introduce kids to an array of music from the last 70 years? Sorry, it'll probably cost too much.
Should your work require you to become more saavy about copyright protection, public domain and fair use [or if you just want a glimpse into the complexities of copyright] try out this handy public domain tool. Props to Molly Sheridan of Mind the Gap for the tip.