Find Blog Posts With Same Niche

I came across this site which searches Wordpress blogs with any key word/ words you type, it gives 1000 posts with related to your niche.

Thought I should post it on here, I use it a lot for finding posts with similar content and leaving relevant comments with my URL and title.

FindBlogPosts.com

If anyone knows a website that searches through Blogger blogs in the same way that this does, please leave it in a comment here. Thanks.