Create a frontend of your own for the Steem Blockchain that only pulls posts using the first tag ‘ideafarm’ and have your posting interface put the ‘ideafarm’ as the first tag. This is how Zappl achieved its goal. Micro payments etc can be implemented with your own SMT when they become available.
It’ll be a lot of work, but if you really want to get it done then go for it.
RE: Discussion: How to make steemit "external content driven"