Can anyone recommend some software for finding niche websites by keywords, which will then let me manage then and also export them as lists. Thanks
No such tools or software in my knowledge. Better is, search on Google with different keyword combination to find your niche related websites and bookmark them ( use bookmarking tools like Diigo or your web browser ).
This is probably the closest thing out there there http://www.influencefinder.com/ Just came out last week