When I starting building websites in ~1998, I looked at what was on the web, it inspired ideas, and I built things.

If I were starting now, my inspiration would possibly be things like: responsive, single-page apps, with ajax, websockets, etc.

I was going everywhere and viewing source and you could basically figure out how everything was made. Now--not so much.

It's not so much 'success' as similarity with popular projects.