Who's the target audience?
High usage blog readers
They have no good way to take notes and remember the posts
Have a bookmark service that also graphs ideas and take notes
Can I make this?
Yes, can make an mvp in a week
Are people currently spending money on it?
A combination of evernote, regular notes or not take notes at all
How will I get the first 25/250 customers?
Advertise with bloggers, and other online information providers / info product producers
If it works, will it be sustainable?
Am I the person to build this business?
Yes, I am solving my own problem