Data from the Samsung laptop. Data from other hard drives I used with the Samsung laptop because it was too small. Data from the ailing 60GB drive I installed in my PowerBook G4 five years ago. Data from other drives associated with that PowerBook. Data from my Chinese mobile phone (the most up-to-date source of contacts). Data from my iPod.
A lot of the process is manual – knowing when I can find something that is newer than installed on an old drive, looking up old bookmarked websites to see if they are still valid, and still point to the same information.
It has been useful to me that the Data Detectors technology in Mac OS 10.5 properly merges contact information – prior Mac OS versions would create a new contact if the email was different, but the name was the same.
Humpty Dumpty is coming back together quite well, other than the fact my internal hard disk will prove to be too small to hold it all.