Over the years I’ve jumped from one phone to another and each time I’ve had a backup of all my contacts on at least three other devices at all time. The latest service I’ve played with is Zyb. Whilst still in Beta it’s a simple to use interface for s60 phones like the N95 that allows you to synchronise all your contacts with one simple action.
Among the features I like are the ability to see which of your other contacts are using the service as well as the easy merging of duplicate entries. That’s particularly interesting when, like me, you’ve had to synchronize across a number of platforms over the years and ended up with a few duplicates. It’s also online which means your contacts are always accessible as long as you’re online should you lose your phone or the batteries die.
In so far as I can tell there is no automatic syncing so the updates are as frequent as you remember to do them unlike with paying services like missingsync where updates are as regular as you are close to the machine you synchronise with.