Gotta say, these resources are useful. It makes life easier with the script present. When I think about all the ways of mastering reading/listening. You need to have a heavy knowledge of kanji in order to reach high-level fluency(3000 kanji?).
I need a tool that would be able to convert Japanese texts with kanji to spaced hiragana, something similar to this http://nihongo.j-talk.com/kanji/, but able to handle large files - novels.
Do you still need this?
I took a fork from MorphMan (written by overture) and added the functionality there. It is available on github as a source download. You will have to copy it into your plug-ins folder. Note if you are using MorphMan already make sure you have a backup of your dbs (just in case).
Open up MorphMan like usual and there should be an extra button at the top that will do what you want. This works on my machine, but has not been tested elsewhere, so not sure of what troubles you might find.