www.arkivmusic.com  Calls itself "the source for classical music" and I won't argue. Seems to have every LP, CD, DVD... on every classical musician who ever lived.

www.thenostalgiamachine.com starts at 1960 and goes up to 2013. Choose a year, then see links to dozens of popular songs from that year. You remember a year as being pretty bad? This site proves it. Or pretty good? This site lets us go back in time.

https://www.apassion4jazz.net/quotations.html Has ten pages of quotes by musicians, most of them jazz. From the first, "Musicians are willing to give their entire lives to a moment, melody, lyric or chord that will stir the soul." -- David Ackert, to the last, "Jazz musicians have some outlaw in them somewhere." -- Mike Zwerin, they're often fascinating.

https://syncopatedtimes.com/ contains a tab to Red Hot Jazz, where we could spend years exploring and not see or hear all of it. Devoted to one of the great periods of American music (1895-1929), in many ways the foundation of all modern American music, this site is an encyclopedia of that era.

www.outsideshore.com/primer/primer  Called "Jazz Improvisation Primer," but this link is also a well-indexed guide to the paths jazz has taken over the decades. For you practicing musicians, it also includes baffling (to me, anyway) instruction and music theory.

http://www.qsl.net/xq2fod/musicus/musicus.html  This is part of a homepage by a most amazing person, an expert amateur in -- are you ready to feel inadequate? -- mountain climbing, photography, woodworking, ham radio, paragliding, kayaking, and of course, music. 

http://philip.greenspun.com/materialism/stereo.html  A small part of a personal website, this one on the equipment we use to enjoy our recorded music. The author, Philip Greenspun, gives his informed thoughts, then steps aside for other fans to voice their own opinions. Lot of fun for those who are passionate about the hardware in their listening rooms. (Greenspun writes well on a lot of other subjects; good site to spend a few hours at.)

Flatpick dot com  Quoting from the site's homepage: "Flatpicking Guitar Magazine is a bi-monthly periodical, and companion audio CD, dedicated to presenting all aspects of the art of flatpicking the acoustic guitar as pioneered by such great guitarists as Doc Watson, Clarence White, Norman Blake, Tony Rice, and Dan Crary. Our goal is to help you increase your own skill level and enjoyment of this fine art as it pertains to the musical genres of bluegrass, old-time, folk, Celtic, Western swing, gypsy jazz, new acoustic music, and acoustic rock. To that end, the magazine primarily focuses on guitar instruction. We also feature articles on rhythm guitar playing, guitar building and maintenance, and we also review flatpicking CDs and instructional books and videos."

http://www.pbs.org/wnet/tavissmiley/tsr/dudamel-conducting-a-life/ Feel free to skip anything about conductor Dudamel. The remainder, on music education in elementary schools, is well worth watching.

http://www.harlem.org/ The deceptively simple website opens to little more than a 1958 group photo in front of a brownstone in New York City. But click on the photo and, in the words of the site's logo, "explore jazz history through one photograph."