Now that I use Flickr, I don't really use it for the Web space like I used to but I really love the ability to sync my Macs. I did a sync last night of my address book & contacts so my iBook is all up-to-date for travelling. I also like to sync my mail settings so when my iBook is set up, I just sync it & I don't have to bother setting up a duplication of my email settings from my main computer.
I also like the ability to pop mail from another account, which I use when I travel. I just wish it weren't blocked at work.
My Mac stuff:
Desktop: MacPro 2.66 GHz Dual-Core Intel Xeon DP, 4GB RAM
Laptop: 17" 2.8 Ghz Macbook Pro, Matte screen
iPods: too many!