[Suggestion] Move to .md over .htm
I find that I am growing to like ownnote more and more. So out of the gate a quick thank you for sharing your work.
I do wish, however, that instead of htm file types that the use of Markdown might be considered. This would allow direct editing of a file with any number of Markdown friendly editors (whether internal or external to owncloud).
Rendering of md files is works quite well in owncloud as does the editor.
If you want to edit your notes localy, see this nice and cool project: ownNoteEditor
Had my thoughts on this as well - if can be supported "within" the current ownNote (e.g. you can name a note "test.js" and could use that to do syntax highlighting, ...). But its difficult to do without breaking the view of notes inside ownCloud...