21 cracking ideas for a hub
1: Write a review about a book read a good book or magazine and write a review on it. Maybe with this you could put an amazon link and earn some commission for selling the book.

2: Review a product or service pick a product in you market niche that people would be interested in. It is better if it is something that you use yourself. There are tons of products that you can get affilliate links on.

3: Review a good popular blog or websitei f readers are not familiar with certain subjects or maybe they might be a internet newbie they might not know about all the different resources available to them. I think they would be pleased that you told them about them.