From my technical LJ (http://dgowers-tech.livejournal.com):

Next/prev color in palette/colormap/swatch actions are IN!
(these work similar to the way you can move to next/prev color in palette when using Deluxe Paint or Pro Motion)

Includes actions that work on colormap, palette, or 'swatch' (the last autodetects whether to use colormap or palette based on whether the image you're editing is indexed or RGB)
Look for them in the next 2.3.x release or 2.4, whichever comes first.

From GIMP's CVS changelog:

2006-05-28  Michael Natterer  <mitch@gimp.org>



        Applied patch from David Gowers which adds actions to select

        palette and colormap colors with actions. Modified the patch quite

        a bit. Fixes bug #130123.



        * app/widgets/gimpcolormapeditor.[ch]

        * app/widgets/gimppaletteeditor.[ch]: add functions get_index()

        which gets the currently selected color's index (optionally the

        index of a passed color), set_index() which sets the selected

        color by index, and max_index() which returns the maximum possible

        color index.



        * app/dialogs/dialogs-constructors.c: changed accordingly.



        * app/actions/context-actions.c

        * app/actions/context-commands.[ch]: actions and callbacks which

        use the new functions.

The basic set of operations are (first, last, next, prev, next-skip, prev-skip, set)
*-skip move by 4s.
Personally I have swatch-foreground-next/prev assigned to left/right cursor keys
, and swatch-foreground-skip-next/prev assigned to shift+left/right cursorkeys via the controllers section of preferences. This mimics Grafx2 (and maybe Deluxepaint? I don't know whether DP supported skipping fwd/back.).
By default, next/prev color in swatch is assigned to 0/9 on the keyboard (the keys with the () brackets)

I'm glad to get this done finally, as it really helped me with doing quick detailing and AA. I hope it will help some people to achieve better quality in their pixelled art.

Another thing of interest which was recently added is clipboard brush(limited to max 512x512 pixels in size) -- you can use the contents of the clipboard as a brush(like Deluxe Paint allowed you to.) -- in conjunction with freehand selection it can be pretty quick and fun to experiment with. Clipboard pattern is also implemented!
 I was not involved in implementing that or the following.

Other recent changes that may be useful to pixellers :

 * Show the clone source even while not painting

 * fixed? bug: palette color order changes when indexed palette PNG is saved

 * Support for importing palettes from the selected pixels only.

 * Eyedropping will set the index into the colormap correctly no
matter how you do it (via CTRL-click with a paint tool or via normal
click with color picker tool)

 * Indexed layers without alpha now show up correctly.

 * Old rect select replaced by new readjustable rect select

Were added after 2.3.8, and will be in the next release too.