I'm not sure this can be counted as being of equal substance with other issues in this series. But it has been noticeable. The forced closure of a single US spam emitting enterprise has dramatically reduced the amount of email spam circulating - and the effects are still evident months later.
Spam is more than an annoyance, it is also a resource burner at a time we need to conserve resources. It's a surprise that the emission would turn out to be largely generated from one source. Possibility: they passed through the spammer community such an attractive offer of services that 80% of the business came their way. Another possibility: they offered massively bulked services to a relatively small bunch of miscreants. I cannot tell, but there were certainly several quite distinct lines of "service" that dried up. Most comprised offers of (Indian-sourced) pharmaceuticals that were either pirates of real medicines (I presume) or out and out snake oil. There seemed to be several separate variants on this. Another line that largely dried up purported to be Russian women offering themselves in the home of a better life overseas. That could well be a variant on the Nigerian scam though.
I should note that I have two email addresses. I don't know how each got infected - I'd sorely love to know about the second infection, since I was trying to keep it clear. Possibly I registered to a relatively legit website with lax security that allowed itself to be scraped for email addresses.
The first address dates back at least 10 years, and was mainly infected by poorly-grammared Nigerian scam offers. These died over time, replaced by a smattering of miscellaneous "offers". It attracts hardly any spam right now, so erstwhile spammers must have either not onsold my address, or the remnants were hooked to that US server.
On my main, newer email, they're mainly tempting me to click on a link. I don't know where they lead, since I don't know that my security protects me sufficiently from link-clicks. And there's only three a week now, effectively taken care of by SpamFighter, but quite frankly overwhelmed by the number of tech mailouts that I haven't bothered unsubscribing from. But at least I have that choice.
Update 13-Jan-09: The spam is back in volume. It took a matter of months to ramp up again. It's unclear whether it's one source that has finally found a new home, or whether it involves a distinct community of spammers which has collectively found a new home.