Using jQuery. I have the following html:
All the world
How w
Just use the plain-JavaScript nextSibling, though you have to 'drop out of' jQuery to use that method (hence the [0]):
var text = $('input:checkbox[name="something"]')[0].nextSibling.nodeValue;
JS Fiddle demo.
And I finally realised what was wrong with my other suggestion, which has been fixed:
var text = $('input:checkbox[name="something"]').parent().contents().filter(
function(){
return this.nodeType === 3 && this.nodeValue.trim() !== '';
}).first().text();
JS Fiddle demo.
And to make sure that you're only getting the textNodes from before the br (though frankly this is becoming overly-complex, and the first suggestion works far more easily and, I suspect reliably):
var text = $('input:checkbox[name="something"]').parent().contents().filter(
function(){
return this.nodeType === 3 && this.nodeValue.trim() !== '' && $(this).prevAll('br').length === 0;
}).text();
JS Fiddle demo.