With the right tools, URLs can be thought of as APIs. To wit, take Perl Monks. You can use Bundle::LWP to make calls against it (as if it were a library).

object => perlmonks.org/index.pl
    method => node_id
    parameter => <number of node to retrieve>
[download]

Why is this important? It allows you to treat remote resources as if they were local.

Of course, you could always use a bit of HTML form magic to accomplish what you want in this case:

<form action=" some other cgi" method="post">
<input type="hidden" name="var1" value="whatever">
<input type="submit" name="go">
</form>
[download]