One of my favourite websites is APOD, Astronomy Picture of the Day. I've been visiting it daily almost since it started in 1993, back in the infancy of the web. Even after all these years, it remains one of my favourite sites, and on my list of sites I check daily (even on weekends). Every day, there's a spectacular new astrophoto to look at, and an explanation with plenty of hyperlinks to follow. Some of the pictures I save and use as desktop backgrounds. This is one of the oldest continuously operating and most enduring non-commercial websites I've encountered, and I hope it sticks around for many more years.