Somehow or other I ended up finding a hosting provider named Site5. They’re currently my front-runner. They offer a guaranteed 99.9% uptime on their shared hosting accounts, and have an interesting “Cloud Hosting” account which promises 99.99% uptime (they claim that in the event of a complete hardware failure, your site will be back up in less than ten minutes; 0.01% uptime is about 4 minutes per month). This latter costs roughly the same as a Pair “advanced” shared hosting account.
The thing that impresses me most about Site5 is their transparency: they have user forums with complaints from users (and responses from the CEO and CTO) out in plain sight, and they have pages showing the status and uptime statistics for all of their servers; judging from my random spelunking of these pages it seems to me that their 99.9% uptime guarantee for shared hosts is slightly optimistic (at least on a monthly basis). I went and looked at a server that had gotten lots of complaints recently, and sure enough its stats sucked.
After seeing how well Site5 does this stuff, I tried googling for server status pages for other hosting providers and pretty much came up empty. (In general, it’s not that there’s not some kind of server status page for most providers, it’s just that it’s useless.)
Uptime
Our local power company advertises 99% uptime. (I may be mis-remembering, it may have been 99.5%.) The point is that 1% of a month is about seven hours (and we do get a lot of outages here, in no small part thanks to frequent thunderstorms and tornadoes). 99.9% uptime is not really all that much to ask — the only downtime I get on my Macs (which aren’t managed by anyone) is for power outages and major system updates every couple of months (which involve a sub-60s reboot). 99.99% uptime is a lot more ambitious.
(By way of comparison, Joyent advertises “telco reliability”, which I guess is “five nines”. (Or, in Alabama, “two nines”.) If I could justify getting a Joyent account, I’d love to, since they’re a big backer of node.js and offer support for it “out of the box”.)