Ignoring the pedantry --- in attempting to view this article, the intro (and apparently link) to it on your site is obscured by a redbubble slide show that I can't seem to get around?

(Running Firefox 21.0 on Win7 64bit for the 2 cents that may be worth.)

Although pinhole is not my primary interest, I have participated in WPPD every year since 2005 and keep using it as an excuse to indulge in some crazy craftsmanship on cameras!

Similar to what Loris describes, I normally make myself a pocket sized chart that goes from an exposure time for f/22 to what's needed for the specific film and camera; using reciprocity compensation if needed. The program Pinhole Designer can actually produce an Excel spreadsheet table** using readings at f/22 and has compensation for a few films built in. I usually reformat and truncate the chart, as a compensated exposure of 1795 hours seems unlikely, since I don't normally add a folding cot to my gear!

** The latest updates of Office 2007 grumble about possible security risks when opening said table, no doubt because the program dates back to the start of the millennium.