How about an extra pseudo operator?
Code:
Ext.DomQuery.pseudos.nodeType = function(c, a){
	var r = [], ri = -1, n;
	for(var i = 0; n = c[i]; i++){
		if(n.nodeType == a){
			r[++ri] = n;
		}
	}
	return r;
};
Now you can simply use:
Code:
Ext.Element.prototype.getChildren = function(){
	return this.select('> *:nodeType(1)');
};