For any size, i use..

HTML::Template in perl, Velocity in Java - Both VERY simple template systems. You can't make it do really "intense" things w/o a lot of work. You can't lazily create crap as easily w/ other template systems. Learning curve is very low.

CGI::Application in perl, Struts in Java - A lot of people know them. I prefer struts for data abstraction from the actual web application, but that's a preference that coding standards can get the rest of the way.

Class::DBI in perl, Hibernate in Java - There are very simple patterns that we tend to screw up, and add a small % of code to our apps. In the case of database stuff, you first have to deal w/ connections failing, preparing statements, putting all of your sql in a central place, relating them back to objects/blessed refs if you are using OOP. It's a lot of stuff to do. w/ class::dbi and hibernate, i can specify how something maps to something else in a more centralized way and not writing much DB code. DBI is a grand thing, but it's time we got past using it for complex apps, just like you would use CGI.pm to create a cgi.