When I joined Steem 6 months ago, there was not a good interface to learn what's happening with your account. And I had been curious with the blockchain, therefore I have created steem.rocks. Today, it's lifetime came to an end.
All operations are indexed to a MySQL database in the background. This requires a good amount of processing power and resources.
steem.rocks needs a private node to catch-up with the chain and respond fast. Public nodes are unstable, private nodes are expensive. I almost switch the nodes every day to keep the site going and it's not sustainable for me.
Busy.org introduced both "activity feed" and "notifications" features recently.
steem.supply gives a good insight about potential rewards.
steemreports reports in/out delegations.
steemian.info lists top400 witnesses.
steemworld gives great information about your account.
I shut down the hosting but the code is still open-source. You can investigate the code, or host your own version.
Special thanks to 
