How to mount ext3 R/W partition

I can think of at least one way (although others may know of better ways). With your spare ext3 partition mounted at some point (such as /mnt/users), change the permissions for the mount point directory.

# chmod -R a+rw /mnt/users

Now anyone should be able to read and write to it.

It might be a little safer, though, to create folders that would be assigned to specific ordinary users.

# mkdir /mnt/users/user1
# chown user1:user1 /mnt/users/user1

and so on for each user. Each user could then create a symbolic link in his home directory to his directory on the ext3 partition.