How to Backup user files
There are many solutions.
rsync
rsync syncs two directories. Works incrementally. With the right magic options, it seems to sync everything needed. Lukas did a script, md hacked it: http://www.iam.unibe.ch/~denker/misc/backupWithRsync.txt
To restore my backup, I proceeded as follows
mount +t hfs -r -o rdonly,noauto,nodev,nosuid,journaled /dev/disk1s1 /Volumes/Backup
and then restored the backup with
rsync -av /Volumes/Backup/macguire/full/ /Users/akuhn
do not omit the / at the end of the first path
Mozy
Mozy provides an interesting on-line encrypted backup service. See http://mozy.com