I'd like to open a discussion that might inspire others to look at places they never even knew existed.
Edit:
Although it may sound like it, I'm not actually looking for a concrete ideas for my own business. Sorry if I made it sound like it. What interests me (and I hope others as well) are general strategies to find one, particularly in crypto. E.g. In what way is it best to look for some emerging trends that might be good to explore?
You are the only one who can make up better ideas. There are lots of ideas but only you can tell if you can manage to handle those along the way. Try to spend some time searching those suggested ones in a silent room, solo or be accompanied by your supposed partners. Try to analyze if those on the lists can handle well - in other words, brainstorming.
Because that is a crypto-related idea, you need someone with basic knowledge about it. Try to search if one of your colleagues might be a help or maybe in your local section. It's easy and more approachable if you will consult there first.