Hosting reliability
I was just looking at Netcraft's February 2009 hosting reliability survey and was impacted by just how many ultra-reliable offerings there are out there nowadays.
Gone are the days when my old host, Rackspace, used to dominate the charts. In fact, they didn't even make the top 10 in February. My new host, INetU, did make it in (in eighth place), but there is no longer much difference at all between coming first and coming tenth. The top 10 hosts are all ridiculously solid.
Notice how all top ten hosts show 0 hours, 0 minutes, and 0 seconds of downtime for the month. The winner failed to respond to only one request in the entire month. The next four providers failed to respond to only two. The others in the top ten failed to respond to only three.
Basically, if you want reliability nowadays you are literally spoiled for choice. You should be making your hosting choices based on customer service (how they respond to your tickets, in both emergency and non-emergency situations) and little else.