I have used (indeed am still using) a number of wordpress plugins. I have actually written quite a few myself as well as several others. There are a few I've used in the past and may well use again, but are currently uninstalled.

They are:

Merge + Minify + Refresh

Used to minimise the size of the css and javascript sent out by wordpress when delivering pages. Not currently simply because it seriously interferes with debugging the javascript!

WP Content Security Policy Plugin

Used to play with the content security policy that allows cautious browsers (and the server) to manage the javascript being used. I did use this to clean up the delivery, but couldn't get to a really clean content policy. I'd still like to do that, but it's not so trivial for the this site (from memory it's mostly the theme that causes trouble).

WP Super Cache

used when the site on dreamhost was an actual wordpress installation to reduce the server load. Since the dreamhost is now just a static version of the site I don't need it there and don't use on the version on my local network since the caching gets in the way of my testing.

WP-DBManager

I have used this to explore the wordpress database. I don't currently need to do this, but would use it if I needed to

WP-RSSImport

Used to query RSS feeds - As I described on the affected page I used to follow a bunch of RSS feeds, but no longer do so (and it's less useful for this static version of the site anyway).

Another plugin I've used but is currently uninstalled is:

Enhanced Media Plugin

Seemingly now unsupported I used to to more easily manage the tags from within the media library. A shame since the standard way is definitely long winded 🙂