- wp-optimize - Clean up your database easily and safely, without manual queries
- woocommerce -The best free and ever growing eCommerce system I have used on an open source platform
- revslider -A great premium slider plugin anyone can use. I think they have decided on a UI so hopefully no more major overhauls. There is a learning curve.
- WP Migrate DB - Migrates your database by running find & replace on URLs and file paths, handling serialized data, and saving an SQL file
I am yet to find a nice plugin that integrates well with Flickr. I have a plugin (Flickr Justified Gallery) that displays a Flickr photostream, but ideally I'd like a plugin that allows me to display all (or a selection) of 'albums' on one page from a Flickr user.