John, are there any cases brought to the WIPO that involve domains that dropped?
Oodles. It's a very common fact pattern.
http://www.wipo.int/amc/en/domains/decisions/html/2002/d2002-1167.html
Respondent is not shown to have done any more than to register a generic domain name that was available for registration and use it in connection with goods which the domain name describes. . The record does not establish that Respondent had knowledge of Complainant or intended to disrupt its business.
Whilst the Panel is sympathetic to the plight of Complainant in light of the evidence in the record indicating that the disputed domain name was made available for registration after Complainantâs renewal payment apparently was paid and after Complainant was informed that its registration had been renewed, Respondent is not shown to have been responsible for that conduct. . The propriety of that conduct and the extent, if any, to which legal avenues outside the Policy may be available to address those circumstances are not issues this Panel is able to address under the Policy.
http://www.adrforum.com/domains/decisions/114434.htm
In this case, Complainant claims that Respondent has intentionally attempted to divert Internet users to competitors and that Respondent's registration of the disputed domain name capitalized on an error on Complainant's part in failing to renew registration of the domain name, which Complainant had originally registered in 1997. Respondent waits for domain names incorporating common words, generic terms, short terms and useful phrases to be released after their registration has lapsed. Then Respondent immediately registers those names and uses each of them to host a generic portal web site, presumably gaining revenue from banner advertisements and affiliate links. This activity has not been found to be bad faith registration or use under the UDRP unless the selection of the domain name and the manner in which it is used are related to its correspondence to Complainant's trademark. It has been held that a party is entitled to conduct a business of capturing generic domain names which become available in the marketplace, often through failure to renew registration. See Canned Foods Inc. v. Ult. Search Inc., FA 96320 (Nat. Arb. Forum Feb. 13, 2001); First American Funds v. Ult. Search, D2000-1840 (WIPO Apr. 20, 2001); GLB Services Interactivos S.A. v. Ultimate Search, Inc., D2002-0189 (WIPO May 29, 2002).
The fact pattern is so common, that it got to the point where I could file a response, wake up the next morning, and wonder what the domain name was.
Now... in circumstances where (a) the prior registrant had established a TM claim in the name, (b) the name is not otherwise a "dictionary word" being used in accordance with its primary meaning, and (c) the subsequent use by the new registrant is consistent with the TM claim, then the decision is going to go the other way.
However, when someone comes out of the box claiming there was a "mistake" or "error" on the part of the registrar, then refer them to their registrar's terms of service, which provide the registrar with the ability to correct mistakes (all of them do), and tell them to sort it out with their registrar, since you have no way of confirming said "mistake".
Quite often, you will not be hearing from the domain registrant, but will be hearing from an outside contractor responsible for their website, who has found himself between a rock and a hard place because he forgot to pay the bill.
be polite, direct and invite them to make an offer if they want to
...unless one genuinely has no interest in selling the domain name. Sometimes a response to a c&d is taken as an "invitation to deal", and the situation becomes something like a Pepe Le Pew cartoon.
ound: 
