Take a definition list with multiple dts and dts as reference for testing.

Wouldn't this be better as a plugin?

jQuery.fn.nextUntil = function(expr) {
    var match = [];

    // We need to figure out which elements to push onto the array
    this.each(function(){
        // Traverse through the sibling nodes
        for( var i = this.nextSibling; i; i = i.nextSibling ) {
            // Make sure that we're only dealing with elements
            if ( i.nodeType != 1 ) continue;

            // If we find a match then we need to stop
            if ( jQuery.filter( expr, [i] ).r.length ) break;

            // Otherwise, add it on to the stack
            match.push( i );
        }
    });

    return this.pushStack( match, arguments );
}; 

This works and is extremly useful when selecting DOM elements. Adding to core is a double-edged sword: We don't want a bigger file size, but it's hard to find this when someone actually needs just this.

While this plugin is quite useful - there are a number of advanced DOM-related functions that I'd like to write. In the end, however, they should probably remain out of core (otherwise, the size would explode). Stuff like:

  .wrapAll()
  .wrapInner()

  .getWrap()
  .getWrapAll()
  .getWrapInner()

  .nextUntil()
  .prevUntil()
  .parentUntil()

  .allAfter()
  .allBefore()

  .addNext()
  .addPrev()
  .addParent()
  .addParents()
  .addFind()

  .addNextUntil()
  .addPrevUntil()
  etc. etc.

Essentially, there should be functions that append to the return object (when they normally replace - see .add*) and there should be functions that return the result (when they normally only modify - see .getWrap*).

Obviously, all of these are useful in their own ways, but combined, it's pretty impractical to add them all into core. I'd like to try and get some feedback on this matter before closing the ticket.

By introducing the non-destructive behaviour, the add* methods wouldn't be necessary. Instead of:

$(...).addNextUntil(...);

you could simply combine existing methods:

var items = $(...);
items.add( items.nextUntil(...) );

Maybe something similar is possible for the get* methods. That would reduce the essential methods down to wrapAll(), wrapInner(), nextUntil() and prevUntil().

What is parentUntil() supposed to do? At first thought, it sounds like the same as parents(...).

Ok, for now I think they should be broken off into a separate package, unless a really elegant way of handling them can be devised.

Yeah - this is going to have to go in a separate plugin. I've got the meat of one kicking around. I'll polish it up and publish it.