I use a Speed Dial extension. Under prior Firefox versions, I used Josip Del Rio's Speed Dial. Under Firefox 57, I use Juraj Mäsiar's Group Speed Dial, from https://fastaddons.com/
The win with GSD was the ability to use a previously exported configuration file from Del Rio's Speed Dial and import it to GSD. GSD doesn't handle the about: dials I had in the old Speed Dial, but that's a Firefox 57 limitation, and I can live without them.
Just want to give a plug for Group Speed Dial by https://fastaddons.com/
On the developer's YouTube channel, he has a video tutorial on how to export from FVD and import into GSD. The trick is to either use another browser, e.g., Chrome, to export from the FVD extension.
If you must use Firefox, you can set extensions.blocklist.enabled to False. But I'd only recommend that as a temporary measure to export your Dials from FVD.
Getting everything set up and looking the way I liked it after importing was a pain, but I'm doing a little more as I find dials that need their thumbnail updated.
I've migrated to Group Speed Dial from https://fastaddons.com/
You can export your Dials from FVD on Chrome, for example, then import them into Group Speed Dials. It's free with cloud sync. There are more customizable options than FVD. There are advanced features, e.g., nesting Dials, that require a Pro subscription.
On the developer's YouTube channel, there is a video tutorial on how to export from FVD and import in GSD.
I've build one just recently, it's called "Web Translate" and although I've build it mainly for the new Thunderbird 78, it works just fine in Firefox / Chrome:
https://fastaddons.com/#web_translate
It's free to use, but not open source.
I'm now working on a new version 2.2 that will add Yandex and DeepL support and fix some bugs :)
"Scroll anywhere" https://fastaddons.com/ if you're into middle-mouse-click-scrolling. By now there are a lot of websites I can only scroll through when I use this extension.