We talked in my Ethnographic Filmmaking class yesterday about field journals. I'm particular to keeping paper journals (which I scan and PDF) but students had some recommendations for online journaling software:
Mac:
PC:
Online:
I should mention that some of my grad students have also experimented with using blogging software set to a privacy mode to blog their fieldnotes.
I also posted an older (but much more extensive) list a while ago: http://www.photoethnography.com/blog/archives/2007/01/fieldnotes-soft.html
