Emacs org-mode: notes, planning, authoring – in plain text

Emacs contains all kinds of craziness, but this is one of the coolest things I've seen in a long time: org-mode is an Emacs mode that does outlining, planning and authoring, all in plain text. A few of the highlights:

• Everything is text. This does have disadvantages, but the advantages are obvious: easily exchanged by email, put into version control, a format many applications understand, etc.
• Outlining
• Hyperlinks to emails, web pages, files, etc. inside content
  
• Meta-data such as tags and dates attached to content
  
• Tables: continuously aligns all the cells of a column and can move columns around.
  
• Spreadsheets: you can perform calculations in tables
  
• Publishing: content can be published as HTML and LaTeX
  

Find more information here:

• The org-mode web site
• Google tech talk on org-mode