As far as Steem based apps, I'd chalk it up to the analytics side. In no particular order, I love SteemTracked, Steemnow, and SteemConnect! I had a thing for checking all the stats my blog accrued over the months, and honestly found it all with steemtracked. I hope it's not suspended indefinitely, because I still like visiting my most popular post from time to time. Steemnow helps me keep up goals for posting regularly; plus I can keep an eye out for users who visit me regularly. Steemconnect comes in last, but certainly not least for the seamless UX it provides. One-click sign-ins? Too right.