Rokapoke - I actually have been kicking around the idea of a pack generating spreadsheet too.
My theory on the color rotation of commons may or may not be true - or may not be true for all sets... but when I open packs, I consistently see a WUBRG ordering in the commons (which rotates through)...
What I was doing to make boosters at work was sort by rarity then by random (for commons it was rarity, color, random).
To simulate a booster box, I used the same randomization for both packs and simply took the top rare, top 3 uncommons, then rotate through the commons in a color cycle. The next pack starts with the 2nd rare, 4th through 6th uncommons, and picks up where the common cycle left off...
It get's tricky when you have artifacts or lands in your commons... I think you could spread them out in the colors (which is what I think WOTC does) when you randomize.
If you have multiple cards in a set (like the 8 card packs) - you could adjust for that as well.
I think this also helps with time spiral - since you simply randomize the Time spiral cards - except I don't know if Wizards actually gave them a true rarity and if you'd want to treat the "common" spiral cards as 3, uncommons as 2, and rares only 1...
I actually have a partial box of Time Spiral left - so the best way for me to generate them is to open up a couple packs....
Trouble is it's a finite amount of packs...
I think with Google Docs, we could share the pack generator to make easy (and consistent) packs... It'd also be easy if we could "seed" the random number generator - so we could get the same results for a pack if we wanted... or use that to document each pack... Another option (a poorer option) would be to generate a booster box of packs - and have people take them one by one out... It would make for an interesting set with some spread out cards and less duplications... (You'd re-randomize commons when you ran out - and uncommons when you ran out).