When "The Lord of the Rings Motion Picture Trilogy" exhibit opened in the beginning of June, it shattered opening-weekend attendance records at the Houston Museum of Natural Science. Visitors from as far away as Los Angeles came dressed in full Rings regalia and stood in line for hours before the museum doors opened, playing medieval instruments and swapping chain-mail tips.

And while no one talks of a wholesale shift from highbrow to pop culture, more museums are using the kitsch and cachet of contemporary phenomena to help balance the books and bring in younger crowds. While these shows can be interesting and well done, they are often peripheral to a museum's mission, say experts...