Last time I wrote about syncing, it was about syncing files over your home network, but I was also curious about Owncloud, an open source cloud server, for syncing over the web. As luck would have it, a couple of links came my way from Owncloud's forums about getting it to run on PowerPC. The first link is a post on compiling for Leopard, and the second points out Owncloud is now in the Debian Jessie repositories. So to get it on Wheezy, just change your apt sources.list to download the Jessie packages before changing back.
ownCloud 1.4.0 client PowerPC Leopard version successful
Desktop client for iBook G4 running Debian Wheezy
Once you have everything running, you can sync with your web server or even your home server, and you get some nifty calendar, contacts, and music features, too.
On a semi-related note, I have a cloud server of sorts with my Mediafire account where I keep uploads like Transmission QT 2.31 and other PowerPC related stuff. I bring this up because Peter S. sent me his version of Open Arena specially compiled for G3s (altivec disabled), so I uploaded it and here's the direct link.
Now thanks to Peter you can have a G3 and still get your Quake 3 game on.