The Mudd's collection of recordings primarily supports the curriculum. However, there are many recordings that can be considered "recreational" listening, too.
Popular music, which includes most "popular" genres except jazz, is found in M1630.18. It's a very broad subject ranging from Frank Sinatra to Jadakiss. Jazz is M1366 and Musicals are generally found in M1508.8, although anthologies and movie music are cataloged differently. If you're not looking for something specific, just plop yourself down in front of one of these sections and let serendipity guide you.
When searching for specific performers, remember that in LUCIA performers are authors. Drop the initial article when searching for or browsing names of groups ("beatles.")
Some Library of Congress Subject Headings to browse in LUCIA are:
These subject often have a range of years tacked on to the end: Jazz--2001-2010. This will tell you the range of years in which the music was created - helpful if you want historic recordings or the latest thing.