I'm using emacs org-mode for various purposes. Most common functionality is to mark my tasks with special tags TODO & DONE. Is there a way to add custom tags (e.g IN_PROGRESS) and highlight it with separate color?
Also, would be good, if this tag roll in the same buffer as TODO and DONE so I can switch between them by using the same hotkeys.
I use the following in my init.el, which sets additional task statuses and their styles for all org files:
(setq org-todo-keyword-faces '( ("NOT-TODO" . (:foreground "blue" :weight bold)) ("IF-TIME" . (:foreground "yellow" :weight bold)) ("NOT-REPRO" . (:foreground "purple" :weight bold)) )) (setq org-todo-keywords '((sequence "TODO" "NOT-TODO" "NOT-REPRO" "IF-TIME" "DONE"))) 
NOT-TODO is a little like WONTFIX, indicating a resolved action item (as opposed to a headline that was never marked for action). I originally started using it when working with testers who were submitting issues that sometimes ended up conflicting with other requirements or constraints. I now use it in my own projects before archiving an item that I changed my mind about, especially if I clocked any time to it. It should always include an explanation, and I now use it with (@) so that I get prompted for a note when setting it.You can do as this in the beginning of the file:
#+TODO: TODO IN-PROGRESS WAITING DONE Press C-c C-c on that line to refresh the setup (not needed for subsequent loads of the file), and everything should be jolly.
As explained here.
I use the following to produce TODO keywords that look a little like buttons to make them stand out more clearly in my outlines and agenda. This styling came from the mailing list if my memory serves me.
(setq org-todo-keywords '((sequence "TODO" "MAYBE" "NEXT" "STARTED" "WAITING" "DELEGATED" "|" "DONE" "DEFERRED" "CANCELLED"))) (setq org-todo-keyword-faces '(("PROJ" :background "blue" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("TODO" :background "red1" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("NEXT" :background "red1" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("STARTED" :background "orange" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("WAITING" :background "yellow" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("DEFERRED" :background "gold" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("DELEGATED" :background "gold" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("MAYBE" :background "gray" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("APPT" :background "red1" :foreground "black" :weight bold :box (:line-width 2 :style released-button)) ("DONE" :background "forest green" :weight bold :box (:line-width 2 :style released-button)) ("CANCELLED" :background "lime green" :foreground "black" :weight bold :box (:line-width 2 :style released-button)))) This makes my agenda look like the following: 
(set-face-attribute 'org-todo nil :background "red1" :foreground "black" :weight 'bold :box '(:line-width 2 :style released-button)). If I find any DONE states left over, I can fix similarly with (set-face-attribute 'org-done ....To add keywords without modifying the specific org file you can modify org-todo-keywords.
See the org manual for more information.
As an alternative to the fine-grained
(setq org-todo-keyword-faces '(... ) which allows you to make adjustments to every TODO state, you might consider a dichotomy approach, which essentially make one face for each of the two groups on either side of the | pipe, for instance
(set-face-attribute 'org-todo nil :foreground "#AFD8AF" ) (set-face-attribute 'org-done nil :foreground "#CC9393" ) (This color choice is my current switch in zenburn theme.) That is, these apply respectively for the groups in
TODO1 TODO2 ... TODOk | DONE1 DONE2 ... DONEn So for instance, 
ETA:
I've since had to wrestle with the fact that various org-mode headline levels have various colorings, and it was too inconvenient to try to find color pairs (for org-todo and org-done) that would contrast nicely with all headline levels. Further, would have to deal with changing Emacs' color-themes, as the low contrast zenburn may be less appropriate as the season changes.
It is much easier to simply invert the default colors. The resulting rectangle edge is a little awkward, so the border helps to make it look a little more natural. Then, I arrive at a scheme much like Stuart Hickinbottom's.
So I now have
(set-face-attribute 'org-todo nil :box '(:line-width 2 :color "grey75" :style released-button) :inverse-video t ) (set-face-attribute 'org-done nil :box '(:line-width 2 :color "grey75" :style released-button) :inverse-video t ) (set-face-attribute 'org-priority nil :inherit font-lock-keyword-face :inverse-video t :box '(:line-width 2 :color "grey75" :style released-button) ) This produces, with init file color choice (load-theme 'deeper-blue t),
(Red as in STOP! Do this! Green as in you are free to go and play.)
