Salt does kill them but you need to see them to do that which menas being up at 3am every night. Which you are.
We need a way to put them off visiting in the first place.
Glad it is not only me who is plagued by indoor snails - they seem to come through the cat-flap to investigate his food dishes.
Salt trails left inside doorsills and across the slug runs will dissuade them, but you will have to remove the bodies. Beer will attract them, but you have to have it deep enough for them to fall in and drown or you will only get more erratic slime trails. Be warned, however, that salt damages metal, paintwork etc.
For outdoors, there are aluminium based slug pellets that don't harm birds, but they do dissove quickly when it rains.
Sharp sand or even builder's sand around the plant bases also works - but the latter can contain salt which some plants don't like. Never seems to bother mine. I even sow my seeds on a trail of sand along the bottom of each drill before covering them with more. Stops them rotting and stops things eating the seedlings.
I use crushed eggshells sprinkled around my lettuce and half plastic bottles to cover young plants and ripening strawberries - the latter also frustrate the birds. The bottles are transparent. May not look too good, but can be camouflaged and are only on the actual plants or fruit bunches for a week or two.
Pepper , chilli powder and cayenne are also effective, but expensive.
Thanks for those tips.
Will look for the aluminium based pellets and also try eggshells around strawbs. 
I have just learned from the coppers blog that Slugs are now on the list of things it is illegal to be cruel to.
So we need to leave the slugs alone.
Really? Whatever next! Soon we will be hearing it's now illegal to be cruel to criminals or something daft like that - hang on a minute, we already did........ 
Well I am a bit of a rebel so will still be mean to them (slugs not criminals -unless they are very small and feeble criminals). I will make cruel and hurtful remarks to them like "yuk you are all slimy" and so on.
If I am arrested I will plead insanity since any more political correctness and it will be true.
"The cost of buying beer just for the darn slugs would probably cost more than the pellets."
It's the yeast they go for: see suggestions here:
http://www.bachmans.com/tipsheets/gardening_problems/ughslugs.cfm
They have a "non-alcohol" beer in the supermarkets in NYC which seems to entice them into the traps pretty well, and quite cheaply. Again, it's the yeast.
Salt works, but you have to be there to sprinkle it, and the subsequent mess of melted slug is revolting.
I pick them up with kitchen paper first and then sprinkle salt on them in the paper and put them and the paper in the bin.
I can offer an evil 9 yrold ( who just announced she believes in Vinegar, Silme and Aliens!* beats the knickers of Cof E!*
who will pour salt on slugs.. it works she cackles and the garden is made un useable cos Plant s dont grow with Salty Soil!
I use a Frisbe filled with beer or cola!
They shrivel up and die! yuk
Alternately i feed them premium grade Hostas! I even sowed a patch of rocket for them..( well for us)
I've just read that slugs are very attracted to saucers of 'going-off milk' and will climb in and obligingly drown themselves.
Should anyone have a problem obtaining supplies of going-off-milk, let me lend them a teenage girl for the week, as they always have half-drunk bottles of the stuff in the bedrooms at varying stages of yoghurtiness.
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