Last weekend's server crash resulting in T-Mobile Sidekick users losing all of their data left a lot of Sidekick users understandably angry. At first, T-Mobile considered recovering the lost data unlikely, but now it seems that most of the data has been recovered and will be restored to Sidekick users shortly.
Part of the problem: Microsoft offers no digital backup for the Sidekick. My iPhone's address book is backed up on my computer, but (similar to my Moleskine addiction) I also keep a paper address book for important phone numbers — just in case. What about you? Do you have your contacts' information stored somewhere so you won't lose it?