The following proposal's value may be really low, nothing revolutionary, but sometimes one may need the code like the following:

// bar is an IEnumerable<T>
foreach ( var foo : bar ) {
    Console.WriteLine(foo);
} else {
    Console.WriteLine("no foos in the bar");
}

Just a little syntax sugar.

EDIT

Please note that there would be no a straightforward extension method: foreach might contain break, continue and return.