This recent post from i>Lior Messinger looks at five frameworks he considers absolutely necessary for every software developer out there:

If you are an architect with a team of developers, or one developer with a team of managers, here's a list of a set of modules, frameworks and strategies you should have in mind. Not all of them would necessarily apply to you, but if I were you, I would at least think about each one. So if you are starting a new project - lucky you - from scratch, or coming to an old project with a mandate for change, here's a small checklist.

The five types are:

• a good ORM (Object Relational Mapping) layer
• a tiered framework (splitting out interface, business and database logic layers)
• a event-based framework
• a caching framework (or some form of easy-to-use caching)
• an error/tracing framework

Some frameworks, like the Zend Framework, come with most of these already built in, reducing the need for more than one sort of technology stack.