On the Scale of Swears, where 1 would be something like “drat”, and 10 would be “f*ck”… “hell” would be about a 3. You probably wouldn’t think twice about saying it, unless in the company of the very young, very old, or very churchified. And even then…
Hell no!! 
Americans are famously puritanical, having received our training from you Brits, Tuco. Thanks a lot! 
So, we have a whole host religious terms that were once considered quite strong swear words (hell, damn, damnation, God, Jesus Christ), and still are by some. We also have a corresponding array of pseudo-cusswords, mainly invented, I think, between the 1st and 2nd Great Fundie Upchucks, er, Great Awakenings (heck, darn, tarnation, gosh, jiminy cricket). “Hell” could still raise hackles even outside the Bible Belt 30 years ago: I once got in trouble in college in Pennsylvania for using the “h” word.
The Bible Belt is apparently expanding, in width at least, at an alarming rate, so who knows how long we’ll be able to swear openly? Since major US corporations don’t have a market in cursing, as they have in porn, it may not be long.
BTW, back in 7th grade, my classmates and I were amazed to find that “bloody” is a swear word in England, and one that was nasty enough to require “ruddy” as a surrogate. Nowadays, Americans use “bloody” on occasion. It has about the same intensity as “heck,” though, so we never needed “ruddy.” Where is it on the intensity scale in Britain these days?
Also BTW, the Word Detective (www.word-detective.com) has a write-up on “tarnation” in this month’s column.
'm srry, bt fck sn’t * 10. bv fck y** hv*, crt**nly, mthrfckr, ccksckr nd cnt.
– Tnbrs, wrkng ndr th mprss**n tht vwls r drt*.
You can learn a lot from the Simpsons:
Homer: “Oh I suppose you’re going to mock me too.”
Bart: “Well actually Dad I believe you.”
Homer: “You do?”
Bart: “Yes I do. You seem so damn sure!”
Homer: “Thank you son. And do you think you could stop the casual swearing?”
Bart: “Hell yes!”
Homer: “That’s my boy!”
Bloody is right there with hell and damn as not swear words at all anymore in my experience. Hell and damn never were in my experience and I’m 49 now. Bloody was at one time a minor one, but not anymore I think. Bloody hell is a common expression.
[tangent]What about “bugger!” and “bollocks!”
I worked with a fellow from Yorkshire who used those wherever I might use a low-level swear word such as hell or damn.[/tangent]
Bugger and bollocks - same thing nowadays in the UK. Bugger was more serious than bloody but now it’s just an expressive word in normal speech although it probably wouldn’t be used on TV prior to the somebody-think-of-the-children 9pm watershed (8pm on satellite sub channels).
Fuck and Cunt are harsher but as far as I can see, swearing per-se has lost its shock value and has become part of normal discourse. The UK just doesn’t take Christianity that seriously anymore, except in an anaemic sort of way so we don’t have the Bible Belt influence. What’s mainstream in the USA in this regard, seems like raving insanity in much of the UK - the whole Jackson nipple thing etc.
We have fundamentalist types but they are very much seen as a lunatic fringe if they try and impose their standards on the media.
Northern Ireland is an exception of course - but just illustrates the gulf between Britain and northern Ireland. ‘Grow the fuck up you medieval savages’ is the thought that goes through our mind when kids from one religion are being spat on by adults from another.
If TV station paranoia can be any guide, in the past two weeks I’ve been forced to read the lips of people saying hell, Jesus and Jeez on late night shows.