Sometime Today, Erle Pereira assembled some asciibets to say:
the real trick here is to be patient b/c if u havent got data on the superblock backups.... these numbers seem relatively common..
17, 32768, 65539, 98304, 131072, 163840, 196608, 229376, 262144 ..
and easy way to get the numbers is to do a mke2fs with the -n option (or something like that). That option tells it not to format the partition, but to just report what it will do. It will tell you where the superblocks are gonna be put.