I've used Text::Template and Template (template toolkit) in a current project. The former is nice, and easy to use, but it died under Taint mode. It's not on my list for web pages anymore.

The latter is almost as easy to use, though it has some strange syntax. If you're going to do PHP-like pages, it's a definite possibility. It's not too complicated, so it's easy to start with. (It may not scale as well as Mason, though.)