Without investing in a new grinder you're looking at something like:
[*]the Wolverine which is a long support which projects out from the bottom of the grinder for scrapers and a pivot for gouges
[*]Tru-grind which is a pivoting platform for gouges and a flat one (which replaces the normal platform) for skews etc
I went with the Tru-Grind as was pretty happy with it, it also has the advantage that there isn't a ruddy great ole sticking out, however I suspect that the Woverine type is possibly faster for scrapers as you just drop the handle in (assuming they're all the same length - otherwise there's set up again).
You can find numerous examples of people's shop made jigs, especially for gouges (which are the tricky ones really) - some out of just wood and others out of metal.
If you move beyond the jig for the dry grinder you enter the discussion around Sharpening systems. The front runners seem to be Tormek and Pro Grind. The Pro-Grind has the USP of a flat bevel which, depending on who you speak to will make little or a massive difference. My personal view is that people have been producing astonishing bowls with hollow bevels for 100's of years so the recent issues reported with the grind causing ripples is either breaking science or a new "racing drivers excuse". I have a Tormek and the most relevant concern around that is that it's absolutely useless at shaping tools - to do this you need a dry grinder (onto which you can now fit Tormek jigs). The Jigs are fantastic - the only thing that is ever said against them is the cost...
Hope this helps.
Miles