My small appreciation for opera focuses more on specific composers like Alban Berg and Puccini than on singers, but WFMU's Beware of the Blog led me to an interesting Pavarotti duet, and YouTube showed me that it was one of a truly strange collection. For example, there is the goofy and gimmicky: with Barry White. The less goofy, but still gimmicky (and I'm a bigger fan of Lou's than of anyone else mentioned on this page): with Lou Reed. Strangely powerful and moving: with James Brown.
Obviously, "This is a Man's World" was a better choice than "Hot Pants" or "Cold Sweat" would have been, although "Please Please Please" might have been interesting. The song's big belting emotions mesh well with a full orchestra, making it pretty operatic before the famous tenor joins in.
YouTube also offers videos of Pavarotti duets with Bono, Sting (what, no Peter Gabriel?), Liza Minelli, Ricky Martin, Meatloaf, Bon Jovi, Bryan Adams (or was it Ryan Adams?), and even the Spice Girls, but I really wasn't interested in these. None could beat the Godfather of Soul.
Only once in my life have I ever told my kids "someday you'll thank me for this": when we brought them to a local James Brown concert less than a year before he died. He was obviously not in his prime, but it was the full band with the full show, and he was very impressive for a man of his age. (Google video has an obstructed view video clip of "I Feel Good" from that show.)