I´ve tried several events plugins, but found them either too bloated for my needs (e.g. including registration and ticketing options) or too simple (just a widget).
Event Organiser offers exactly what I was looking for: a simple, but powerful interface that allows for event date/time, tags/categories and venues/location.
The pugin comes with a few default widgets to display events. And if you´re a theme developer (or just someone not afraid to get their hands dirty) you´ll appreciate the functions this plugin offers. They make templating a breeze (to see examples of how I´m using this plugin have a look here).
Last but not least: the author is a great WordPress developer (just have a look at his answers at wordpress.stackexchange.com) so no need to worry about code quality.
I highly recommend this plugin.