Dynamic template assignment for the site

I am not a expert in Drupal. I was thinking if there is any way out for tell Drupal during module render, which template to use for the page other than page.tpl.php.

Its like I wanna show a popup without any header/footer or blocks, just wanna show the content rendered in the module. Is there any chance to tell Drupal inside module, which template to use when ??

There is a way, if i could copy the page.tpl.php and rename it like page-{modulename}.tpl.php, Drupal will use it as template for that module. But problem is that, in that case I have create lot of templates for every popup/module.

What i want to create 2/3 templates, and tell at the module level, which one to use when. If not assign any, the default page.tpl.php will be used.

thanks in advance