I've got 3 5-bay Sans Digital external enclosures, a handful of bare drives, and a spare caddy. Using the eSATA port multiplier I essentially mount a bunch of independent drives in a media directory tree.
I've got physical back-ups of maybe 2-3TB of 'favorite stuff' that I don't want to lose.
I don't think the majority of today's big storage drives are dependable in RAID unless designated as such, and even with the floods you can still find 2TB drives for around $100. Over the years I've simply been rotating in larger drives - haven't made the leap to 3TB just, yet but hopefully that time will arrive at a price point much less than $100.
Most is recorded TV -- everything from The Simpsons to PBS. With my directory structure I stash folders across multiple drives so that if one drive crashes I don't lose more than 15% of any one show.