I released a new free WordPress plugin shortly after reading this post here, so of course I tried out some of the suggestions given here. This is how it went:

- Contact WPtavern: No response so far. I did not expect the world here and know you are busy but still just a short 1-liner a la "Thanks for your submission and we will consider it" would give the whole submission thing a much nicer feel, especially since you suggest it here. :)

- Submit to reddit: My link there got 4 clicks, 3 upvotes and 1 comment. In general the r/WordpressPlugins subreddit is very empty and only has 400 subscribers. If you have a reddit account (as I did) it is worth a shot, otherwise I would not bother. r/Wordpress is much bigger (> 15000 subscribers) but does not allow self-promotional posts by plugin authors unfortunately.

- Contact other WP news sites and blogs: I sent a short message to several other sites, including the ones that have replied in the comments here. Results were mixed of course, with some not replying, some quick "we will check it out" answers but some positive results too. Definitely worth a shot - as everything in life it will work much better if you already have some contacts and know people (Most positive answers I got were from people I was in contact with before)

- Comment on old on-topic posts: Another thing I did that is not mentioned here yet. Simply search Google for posts related to what your plugin does and leave a short comment. Results probably won't be impressive but it can get the word out there a big (to the site owners as well as people finding the posts in search).

My plugin in question is WP Inject (http://wordpress.org/plugins/wp-inject/), a tool to quickly find and insert free creative commons images and as such already something that could be useful to a lot of bloggers. For a more niche plugin it would be even harder to get some traction I would imagine.