More entropy at work.
My DSL line is being flaky: actually my landline phone service is at fault. I ended up moving the DSL modem/interface into another room and pulling cable back to the Airport. Of course, I have an Airport that dates back to the 20th Century with just one Ethernet jack, so I had to leave the wired network offline and just support wireless connections. This of course meant that this website was offline, and anything hanging off the wired side of things — like my iTunes music collection or printing — was also unavailable.
Things seems normal now, so all is back as it should be.
I am looking into getting a newer Airport Extreme (with two Ethernet jacks and possibly an Extreme card: I have one in the iBook but have never knowingly used it in an 802.11g network). Power-over-Ethernet sounds like a good idea; I guess I had forgotten they offered that. Though the used/eBay market may not yield one that snazzy.
For reasons unknown, Google AdSense cashed me out today, paying me the $60 I earned. That will help.