Thanks to everyone who contributed to my reward bounty to provide a list of contests that Steemians are running. I reviewed the results, and assembled my recommendations for users to check out.
Here is a list of contests that users can participate in to potentially earn STEEM/SBD. If you recruit new people to the platform, I recommend you have them check these out - because they are great ways to get involved and earn some extra coins!
Steemit Photo Challenge
This is one of the platforms longest running and most popular contests! Run by 
Hive account@jamtaylor and sponsored by 
Hive account@berniesanders, every week there is a new topic for photographers. They submit up to three enteries that meet the theme, and then all of the entries are judged. The top three picks win SBD prices, as well as all of the honorable mentions. Over $75 SBD in prizes are paid out each week! You can view enteries as well as find the weekly topic post from jamtaylor here.
Meme challenge
If you haven't heard of the Meme challenge yet, check it out! Run by 
Hive account@fibra59 and sponsored by many users - this is one of the most entertaining contests on the platform! Each round a new picture is posted, and users update the photo with their own meme. Some of these are really hilarious!! Entries as well as the latest/current contest can be found here: memechallenge. There is also a "memechallenge" group in Steemit.chat :)
Steemit Culinary Challenge
This is a really fun contest for Steemians interested in cooking! The contest is run by 
Hive account@woman-onthe-wing and sponsored by 
Hive account@smooth and 
Hive account@sirwinchester. Each week a new theme is posted, and participants create a dish/meal following the theme. They post pictures of their dish (being cooked and the final product), and then all of the entries are judged. You can view the contest and entries under the tag steemitculinarychallenge.
Open Mic Week
Want to try out your skills at making a music video? Record yourself singing, and submit it to Open Mic Week. This is a really fun contest run by 
Hive account@luzcypher, and sponsored by Hive account@luzcypher and 
Hive account@pfunk. Even if you don't feel like participating yourself, I still recommend you check out the contest and watch the entries. There are some really awesome/talented individuals, and it is a lot of fun to watch! You can view the latest contest and entries here.
The Wild and Strange Contest
This one looks like a lot of fun! Hosted and sponsored by 
Hive account@papa-pepper. The contest cycles through five rounds, where users can participate by submitting photography, art, memes, poetry, and music (singing). You can participate in some of the rounds, or all of them. There is something for everyone here! There is currently not a dedicated tag for this, but if you browse through Hive account@papa-pepper's blog, you will find it. Here is an example post: season 4, round 4.
Beautiful Sunday Challenge
Want to to create a post that tells a beautyful story? Post it on Sunday using the tag "beautifulsunday", to be entered in this contest. Hosted and sponsored by 
Hive account@ace108, this is a great way to earn extra STEEM by posting great quality content! You can read about the rules in this post, and view the entries here.
Win 5 Steem Dollars Writing Contest
Hive account@looftee hosts and sponsors a contest each week to give away 5 SBD to the selected winner of a writing contests. Each week there is a new topic, and then a winner is selected. You can find them by checking out Hive account@looftee's blog. Here is the latest example: What is Steemit to you?
What on Earth
This is a really interesting contest run by 
Hive account@steve-walschot. Each round, a picture is posted and participants have to guess what it is. All of the contests are posted under the 
Hive account@whatonearth account.
Comment of the Day
This is a contest run by 
Hive account@acidyo where users can nominate their favorite comments. The people who nominate get awarded by upvotes and a share of the post rewards, but the real winners are the people who's comments get selected! The winning comments receive a lot of upvotes, and a portion of the payout from the contest post. You can check out the contest here.
Daily Health Score
The purpose of the Daily Health Score is to help Steemians become more conscious of their health over time. Enter by answering some basic questions about your daily health. One entry will be randomly selected and awarded all of the liquid rewards from the post. Follow the user 
Hive account@steemit-health to see the daily entry posts.
Guess The Word
Several times a week, 
Hive account@steemcollator posts a new word with the first and last letters missing. Example _ _ EEM _ _ (STEEMIT). Users guess what the word is, and whoever wins gets a 50% split of the post rewards.
Poetry Dice
A weekly contest run by 
Hive account@robyneggs, users make a poem, short story, or art piece using all 9 symbols displayed on the dice. The best piece is awarded 50 STEEM. Users can follow the user Hive account@robyneggs, or search through the dice tag to view the entry posts.
50 Word Story Contest
Run by 
Hive account@ogochukwu, and sponsored by 
Hive account@the-future, the weekly 50 word story contest is a great way for Steeminans to try out their writing skills. Each week, a new word is posted, and users must write a 50 word story surrounding/using the word of the week. Winners earn trail coins and STEEM. The contest is only open to users with reputation 55 and below though. You can check out the contest and entries here!
Art Challenge
Don't let the title scare you away :) There is no need to be an artist to participate in this contest. Participants write a comment or post with their interpretation of the photo posted. Selected winners of the best comments win STEEM. The contest is run and sponsored by 
Hive account@aksinya. You can check out the contest and entries here!
If users have any additional contests to recommend, feel free to add them in the comments!
Reminder to vote for witnesses!
The Steem witnesses are the elected leaders of the community that power the blockchain. If you aren't sure who to vote for, you can check out this Witness Voting Guide. If you think I am doing a good job as witness, I would really appreciate your vote!
You can vote for witnesses here: https://steemit.com/~witnesses
