Here's a few that you missed...
Parley - A Decentralized Discussion Engine Based on Steem
https://steempeak.com/ - Steemit with a much better interface.
https://dmania.lol/ - Memes
https://www.parley.io/ - Reddit competitor -
https://musing.io/ - Quora competitor, presumably
https://steemfilter.space/ - Find new content on Steemit
https://steembottracker.com/ - Track Steemit bots
Lovely, thanks @mattcreate, will add these to the list. Steemfilter looks promising for highlighting quality content. Parley has already been added to our forthcoming update, looks interesting too.