In the past I have always used jQuery Lightbox For Native Galleries, a great little plugin that adds a great lightbox effect to your WordPress galleries. However since Jetpack from WordPress.com actually grew up and became useful the plugin author discontinued the plugin in favour of the built in carousel in Jetpack.
As part of my introduction to Jetpack on Wptuts+ here’s a nice little demo of how it looks. It’s super simple to use requiring almost zero configuration! All the below images are generated from Flickholder and credited individually.