A complete sidebar, but something for the people reading this. There are other things that are somewhat app-specific, but have some good points that can be built upon or even just taken if the license permits.
I hate tooting my own horn, but a few people have found it worth stealing for their projects: Mango::Form. It uses a hybrid config of CGI::FormBuilder for the form definitions with FormValidator::Simple config for the validation all in the same config file. The CGI::FB validation wasn't as good as FV::S for me, so the two got married together.