Please add to the list by doing a branch if you think there are more ideas.
1. Twitter/Gettr (just add status updates and we have twitter + 10 ideas a day)
2. Trello: change the format of lists to look like Trello
3. Junglesmash (the idea challenge each month is: Make an ad for X (where X is a brand).
4. A social network of gratitude journals
5. Quora (where idea lists are answers to "Questions" (a re-doing of challenges).
6. Pinterest (change formatting to look like Pinterest. Every idea requires pictures. For instance, "10 shirts I like".
7. Dating site: "10 reasons someone should date me". Or the idea list can be more specific where the first idea is a picture, etc.
8. A crowdsourced news site. Every day there could be a challenge "What are the top 10 news articles one should read this morning" and people will be considered "Editors" if they get enough likes. Maybe even get a cut of ads on their stuff
9. A review site: A 1000 categories listed. The challenge is: pick a category, pick your top 10 products in that category and why.
10. Stock Photo/Media library for use. A photographer can put their top 10 photos about X. And the site can facilitate transactions on those.