To some extent it will depend on what the significant ideas are, but in most cases a simple web page of some kind seems perfectly adequate.

For those that need regular reinforcement of habits you can set reminders for yourself if you need to. I doubt that there are many that actually need a standalone app.

Not a genre that I have spent a great deal of time on - largely because I have yet to encounter one that wouldn't be better summed up as a handful of powerpoint slides or a wiki page etc - and of course most of the standard/popular ones do have summaries like this on the web somewhere or another.

There are ideas in some of the books that 'work', obviously, but I don't think that book format is the best way to get those ideas across - at least to me. 90% of the books that I have looked at are just anecdotes and repetition - and outright snake oil too in some - probably a lot of - cases.

The key thing is to put any useful ideas into practice - regardless of how you discover them.