There are a wide variety of wordpress plugins that you can use to enhance your wordpress blog and improve it, but which plugins do you use that you swear by?

 

Are there any particular plugins that you feel are highly important and should be used by anyone that runs a wordpress blog? If so, which plugins are they?

 

Are there any plugins that you feel aren’t so important?

I use Wordpress for my blog but I haven't used any of the plug-in's yet. I would be curious to see how everyone else answers the questions though.