Adding to Erik's post about tylenol and ascorbate, I do have some success with this but it still needs work. I use parodinal with vitamin-c and borax to make a pretty good developer. Advantages over straight parodinal are less grain and working strength solution longevity.
I use parodinal from Donald Qualls as follows:
Water - 250mL
Acetaminophen - 15g
Sodium Sulfite - 50g
Sodium Hydroxide - 20g
Mix in order indicated, let stand in sealed container 72 hours before using. Keep crystals from bottom of container with liquid when decanting, stir before drawing off concentrate for dilution. Use dilutions and times as for Agfa Rodinal. Use within 30 minutes of dilution.
To make RCB (Rodinal / Vitamin-C / Borax), I use the following:
Borax Saturate Solution - 400mL
Ascorbic Acid - 6g
Parodinal - 40mL
Water to make 1L
This developer is quite active with good speed and relatively fine grain. The grain with normal development is about the same as PCB with minimal agitation. This is much better than my current best with Caffenol-C and much better than normal rodinal development. There is no fog.
Here is a sample from the "corner of horror":
This is Tri-X, EI 400, in RCB for 7:30 @ 19C with normal agitation.
The working strength solution has been in a closed bottle for 2 weeks now and shows the same level of activity. As with PCB it appears that the ascorbate is preserving the p-aminophenol. I found that using parodinal like normal and adding ascrobate increases activity but causes significant fog. I also found that using parodinal like normal with borax significantly reduces activity (expected ... lowers pH) but improves grain. I figured that ascorbate would maximize activity and adding enough borax would keep the pH down for good grain and I got RCB.
My only real complaint with this is the use of sodium sulfite as this is still a somewhat specialized photo chemical and it would be nice to do without it.