diamond 1-16
Iron 1-64
Coal 1-?? (seems to be anywhere)
as for the others, I have no idea, as I used to play with different tin/copper, but they seem to be at least 1-64 as you can usually find copper at cave entrance.
yeah, but I used to use the IC2 ones before FTB, and the copper was not spawning below 10...
What I said do apply to the newer versions of FTB packs (Mindcrack and DW20)
And I do often find copper near the ground level, but I can't remember finding it on cliff side, so 1-64 seems about right.
Tin might be a little lower, and silver is definitely lower 64, but everything seems to start at the very bottom.
If you really want the info, you could try to dig a 3x3 chuncks one layer at a time, and see where the first of each kind appears, it won't be perfect, but will be a good approximation for all the common ores.
All I wanted was to give you the information I had, if you answer like that, just do it yourself.