Maybe it's just because is Monday but, besides of the Julian Assange's example and the time capsule, I can't think of another use case of a Time-lock crypto puzzle, anyone?
Court proceedings that would be sealed for 100 years. Secret material, say military records, that need to be secure in the present, but are important historically at some point. You could provide a declassification schedule this way.
You could do a delayed form of historical whistleblowing or confession, so that it doesn't cause you problems today, but history can know what really happened.
Perhaps providing the equivalent of a 'sealed envelope' to prove that something was known or happened on a given date, without having to be present or active to prove it.
It's fun to think of a puzzle, but presuming it was truly delivering on the safety promise, I can see quite a few uses. The real schemes though depend on a lot of varying factors, so in cases where the secrecy was critical, you can see why people wouldn't use it.
According to FutureCrypt.com, time-release encryption can be used for Sealed Bids, Competitive Proposals, and Press Releases. So things like sealed bids for government RFPs could be transmitted electronically rather than "sealed" in a FedEx envelope. Full disclosure: I own FutureCrypt.
Even Assange's example is suspect. The goal is not to release the documents eventually but to release the documents if he dies under suspicious circumstances. That is not really something that can be done with cryptography.
Here is one possible use case: imagine an offline digital cash system, so i.e. the bank will not accept the same token twice. To protect against an unscrupulous seller, the buyer pays by giving the seller a time-lock puzzle with the tokens; if the goods are not delivered by some deadline, the buyer will deposit the tokens at the bank, thus preventing the seller from doing so. Otherwise the seller solves the puzzle and makes the deposit. This is basically an anonymity-preserving escrow service, though in practice there are probably simpler approaches.
I am sure you read about the early-access scandal at Reuters [0], which the quants found especially spooky as they (by definition) weren't first. So releasing high-value financial information this way is my first idea for a use case.
Clarification: it seems Reuters intentionally sold the info to high value customers early. But this is an even better reason for the information source to release their info this way.
If you want to leave something that you are sure won't be accessed before your death (and you don't want to have to trust some third party). Although I guess it might fit the definition of "time capsule".
