1) Make /mnt/sdcard writable
mount -o rw,remount /sdcard
chmod 777 /mnt/sdcard
2) Get mkfs.yaffs2 from http://code.google.com/p/android-group-korea/downloads/detail?name=mkfs.yaffs2.arm.
3) adbpush mkfs.yaffs2.arm /mnt/sdcard/mkfs.yaffs2
4) adb shell
5) cd /
6) chmod 755 /mnt/sdcard/mkfs.yaffs2
7) Get all content under /datainto a YAFF(Yet another Flash File System) image filedata.img.
/mnt/sdcard/mkfs.yaffs2 /data data.img
8) adb pull /mnt/sdcard/data.img
9) Then, download YAFFEY(Yet Another Flash File (System) Editor YEAH!) from http://code.google.com/p/yaffey/
10) Then, run YAFFEY to browse the data.img file.