https://steemlookup.com/#/ This is generally used by Curie curators to find the best posts. This website shows you all the posts based on your search results incuding word count, specific words, pending payout and much more.

https://steembottracker.com/delegation.html - Many Steemians think delegation is complicated or are afraid they won't be able to get their SP back. This website shows exactly who you delegate to and is very easy to use for adjusting delegations. You will need Steemconnect for this.

https://steemdb.com/@kristyglas (replace username). I use this site to check resteems mostly, because if you take a post link and replace steemit.com with steemdb.com it will take you to a new page where you can check reblogs/resteems and even edit history. An example: https://steemdb.com/artzone/@kristyglas/-s6pgfajwgs

Gina bot- this one is a little more complex but it has saved me lots of time. Also I never miss any entries to my contests or mentions of me even without "@" for the username. I found a detailed tutorial here for how to set it up: https://steemit.com/ginabot/@dynamicgreentk/ginabot-how-to
It's especially useful for never missing posts of your favorite Steemians ^^

Good luck!