Please don't use slug pellets.They will poison the slugs and snails,and therefore,the birds,frogs,hedgehogs etc, who feed on them.I have the same problem,and,have tried all those too.I have to say,that although some gardeners think this is a counter productive method,I have had the best results really,by using a beer-trap. I also do the torch light search,cos,its amazing how many you can find!
I agree with what lindapinda says, except for the beer trap, these things, along with pellets, are designed to attract the little darlings, that being the case, if you use them you'll find your neighbours gardens will be clear of slugs, they'll all be in your garden.
The problem with salt,is that it only works when you see particular slugs etc,and can then put salt directly on them.It's not the answer for general garden use,cos,you obviously can't scatter salt around soil to catch the slugs you can't see.