As a full-time web designer I have a “go to” list of plugins that I use over and over again. Here are just a few:
All in One Event Calendar – this calendar plugin available at wordpress.org and time.ly has evolved into a pretty nice plugin . It went through some awkward teenage years after being taken over by Time.ly but now it seems to work and play well with others. Newer features included the ability to change colors on most parts without editing css. However, the use of themes allows developers the ability to really customize the different views.
Event Manager – Want an event calendar that does everything? This is it. It is more for events rather than just a basic calendar. But if you need to customize how events are listed this is your plugin. The documentation is very rich and loaded with info.
PowerPress – This is my go to plugin for audio podcasting. I actually prefer it over Sermon Browser for church sites. Very easy to set up and you can submit to iTunes straight from the plugin. It gives you choices of players including html 5. You can do different categories or channels. I’ve even used it on sites just for audio without it being a podcast.
WP UI – Tabs, Accordions, Sliders – I really like this plugin. I was worried that it had been abandoned by its developer. It stopped working correctly after WP 3.5 rolled out. (The spoiler code worked so I just switch my content to that.) It was recently updated fixing a lot of issues. You can even “roll your own theme” using the jQuery Theme Roller. Great for displaying lots of text in a small area.