The site is not particularly Bitcoin-related -- but as I've followed Bitcoin's development over the years, I've noticed that many users of Bitcoin think long-term, and I could imagine the site might be useful in a small way for some of you. For example, you could use it to store an encrypted ECDSA private key and pass it on to a family member in 10 years automatically, unless you cancel the message. Or you could do something similar to enact a kind of "forced savings," or just a long-term backup. Of course, you might use it for messages entirely unrelated to Bitcoin too.
The service is free for up to two messages per day. It accepts contributions, and it has an "upgraded" service level that allows unlimited messages (within reason) and a variety of other features, like recurring message. Our subscription fee has been $12/year. We've priced Bitcoin payments proportionally for now; that is, at the moment, we'll use the general prevailing exchange rate for all subscription payments over 0.1 BTC, rounding the length of the subscription in subscribers' favor if there's any ambiguity (sharp price changes or what not). So, for example, at $55-$60/BTC or so, you'd get a six-month subscription for 0.1 BTC.
Time Cave has a long and interesting history. Please don't judge the site on its graphics! The front-end hasn't been updated since 2000, so it's very much a "retro" service. No Web 2.0, no heavy use of JavaScript, no connection to various irritating social-media sites. No web ads or privacy-invading features. But the back-end is rock solid and has delivered millions of messages, many over long periods of time. Obviously, Outlook and other clients can do similar things today, but Time Cave doesn't rely on any particular client, and it's not dependent on GMail or some other large service.
I'd love any comments you've got in addition to questions about the site's Bitcoin acceptance.
PS -- Please don't make timecave.com a target of attacks!
We don't run a Bitcoin node on that server, and we don't store private keys on any online systems. The server has a bulk set of addresses, not unlike those that can be generated by bitaddress.org, and it assigns them to individual accounts to track payments. It's all very rudimentary now, but it seems like a simple way for a service-based website to accept Bitcoin and price services accordingly; it took something like 20 lines of code to add the feature from scratch.