OK guys, thanks for the thousands of comments here :P
I sifted through the multitudes of useful suggestions and distilled them down to the 2 best professions. I also had a little help from HolyPaladin.com and Galo's comment yesterday on Profession Changes in 3.2.
...and don't forget Archie, who got first post in the comments with the very same answer!
So the answer to my question, The Best Professions For a Holy Paladin ...
Jewelcrafting and Blacksmithing.
That is the summary, for the in-depth (kinda) analysis you need to go back to the original article.
Coming up next, a post about Holy Paladin Glyphs.