On one 400GB hard drive I've got:
(hd0,0) sda1 = swap (1gb) primary
(hd0,1) sda2 = mastergrub (1gb) primary
(hd0,2) sda3 = mydata (~231gb) primary
(hd0,3) sda4 = extended (~N/Agb)
(hd0,4) sda5 = Kubuntu Hardy x64 (~15gb)
(hd0,5) sda6 = Custom Hardy (~15gb)
(hd0,6) sda7 = Ultimate x64 (~15gb)
(hd0,7) sda8 = OS not installed (~15gb)
(hd0,8) sda9 = Intrepid x86 (~15gb)
(hd0,9) sda10 = Intrepid x86_64 (~15gb)
(hd0,10) sda11 = Busted slackware 12.1 (lol lilo didn't install right:P GRUB FTW!) (~15gb)
(hd0,11) sda12 = OS not installed (~15gb)
(hd0,12) sda13 = OS not installed (~15gb)
(hd0,13) sda14 = OS not installed (~15gb)
(hd0,14) sda15 = OS not installed (~15gb)
I originally was thinking of setting up a hide/unhide partition scheme with grub so I could get 44 partitions, but I don't really have a need for it at this point.
This is by far the best information on hard drive partitions I have ever come across and I'm sold:
http://www.justlinux.com/forum/showthread.php?p=861282