Anyone happen to know what they're all about? Generally
Mozilla/5.0 (compatible; PageAnalyzer/1.5;)
from 5.189.144 (Contabo* hosting, now blocked) though I've also seen a 1.1 version from a different IP. They showed up suddenly about 10 May and have been vigorously requesting the front page of every imaginable site every few days. No robots.txt, of course.
* Latin for "I will count up my profits", apparently.