[i.o.]

var re:RegExp = /<li\s*>\s*<a\s*href="(.+?)"/gim;
var input:String = ''
	+ '<li><a href="/something/somethingelse/">Что-то</a>'
	+ '<li >  <a href="/something/somethingelse2/">Что-то</a>'
	+ ' \r\n <li  \n   > \r\n <a href="/something/somethingelse3/">Что-то</a>';
 
var matches:Array = [];
while (true) {
	var match:Array = re.exec(input);
	if (match) {
		matches.push(match);
	} else {
		break;
	}
 
}
 
var links:Array = matches.map(function(match:Array, index:int, arr:Array):String {
	return match[1];
});
 
trace(links.join("\n"));

На выходе:

/something/somethingelse/
/something/somethingelse2/
/something/somethingelse3/