Ask HN: To those with successful browser extension(s), how did you grow it?

I maintain a handful of browser extensions and one of them is gaining traction. I'm now looking for marketing avenues and curious to hear from anyone that may have gone down this path before.

Since it appears the Firefox and Chrome stores themselves don't offer any kind of visibility-boosting features, are there any other tools/services you've found useful to increase the number of active weekly users?