First try at online backup: Carbonite
(It's been a while.)
After having to make an impromptu rebuild of my main machine, and watching and hearing many of my old (8+ years) outboard disks make nasty grinding noises, I decided to try one of the many online backup services. After looking through a few reviews, I decided to try Carbonite.
FAIL.
I installed the software on or about June 2, and waited...and waited. While I had a sizable amount of data to move (70+GiB) and was warned that it would take some time to back all that up, I didn't expect for it to hang continuously for 2+ weeks and get repeatedly stuck.
The typical methods for dealing with this problem (reboot? reinstall? turn off your firewall?) were to no avail. Customer service at Carbonite was polite, but stuck to their scripts too much. I attempted to escalate, and was in fact given an "inside track" by whoever listens to @Carbonite on Twitter. But it was too little, too late. If the backup service and software combination doesn't work "out of the box" on a freshly-rebuilt machine with very little on it.
On to try something else.