with a form, just set method to "post"
<form action="blah.php" method="post">
<input type="text" name="data" value="mydata" />
<input type="submit" />
</form>
You can create an html page with a form, having method="post" and action="yourdesiredurl" and open it with your browser.
As an alternative, there are some browser plugins for developers that allow you to do that, like Web Developer Toolbar for Firefox
Source: Stackoverflow.com