1. If you need to return several things for the container to find,
just use more tuples.  I have {title, X}, {head, X}, {onload, X}, etc.

2. ErlTl works just fine with this.  The code looks like:

<%@ index(Beer) %>
<% {title, ["BeerRiot - ", beer:name(Beer)]} %>
<% {head, <<"<script>...</script>">>} %>

3. My container controller picks each of these piece out using two
rules:
  a. all such tuples must be at the start of the rendered data
  b. all such tuples must be in a defined order

So, the container code looks roughly like:

index(Data) ->
    case Data of
        [{title, Title} | TData] -> ok;
        TData -> Title = "BeerRiot"
    end,
    case TData of
        [{head, Head} | HData] -> ok;
        HData -> Head = <<>>
    end
...
    {data, {Title, Head, OtherData}}.

I have to play a few more tricks, though, to account for newlines in
the rendered Data list.  That could be fixed by moving the ErlTl
statements all to one line, but it didn't seem important enough to
worry about.

So, that restricts using these tuples to the "top level" component
view, but it has worked pretty well for me so far.

The idea of adding a {meta, X} tuple to the list of things a
controller can return sounds interesting, but since this stuff is more
on the view side, it also seems a little out of place.  Not to say
that my hack isn't further out of place, of course.  ;)

-Bryan

P.S.  If you think the idea of a beer_controller is great, you'll love
that I also have a beer_container_controller, but only because I
couldn't decide among bottle_controller, can_controller, and
keg_controller.  :)