My favourites so far:

1. Stephanie Hurlburt has a list of developers willing to mentor others:

http://stephaniehurlburt.com/blog/2016/11/14/list-of-enginee...

Some resources from that list:

- https://ishansharma.github.io/twitter-mentors/

- https://mentorlist.herokuapp.com

2. I've used and enjoyed Codementor's “find an expert” for paid help:

https://www.codementor.io/experts