.pushStack idea

jquery-pushstack.js

// currently
jQuery.fn.extend({
  foo: function(selector) {
    // create new elems set somehow
    return this.pushStack(elems, "foo", selector);
  },
  bar: function(selector) {
    // create new elems set somehow
    return this.pushStack(elems, "bar", selector);
  },
  baz: function(selector) {
    // create new elems set somehow
    return this.pushStack(elems, "baz", selector);
  }
});

// removing the 3rd argument from .pushStack
jQuery.fn.extend({
  foo: function(selector) {
    // create new elems set somehow
    return this.pushStack(elems, "foo");
  },
  bar: function(selector) {
    // create new elems set somehow
    return this.pushStack(elems, "bar");
  },
  baz: function(selector) {
    // create new elems set somehow
    return this.pushStack(elems, "baz");
  }
});

// factory that keeps the 2nd .pushStack argument, and makes things smaller
$.each({
  foo: function(selector) {
    // create new elems set somehow
    return elems;
  },
  bar: function(selector) {
    // create new elems set somehow
    return elems;
  },
  baz: function(selector) {
    // create new elems set somehow
    return elems;
  }
}, function(method, fn) {
  jQuery.fn[method] = function() {
    return this.pushStack(fn.apply(this, arguments), method);
  };
});

Note: completely untested.

Also, perhaps the callback to $.each in the third example could be a reusable $.pushStackify method.