I'll kick things off with a little Git - my new favourite version control system. Its very cool - I really like being able to have both a local and remote history - what a great way to work.
For a solid introduction to how to use it I suggest checking out Git Immersion by Edgecase - its an easy read and covers all the basics.
I followed the guide on Stop Reading Here! on how to setup Git on the my DS210j - it was pretty painless. It was probably made easier by the fact I'd already enabled/installed the necessary prerequisites when I installed Subversion on it last year.
The DS210j is a great little NAS - I originally chose it primarily because it was one of the few feature rich NAS devices that supported TimeMachine. I'm really pleased with it - I have 2 1.5TB disks in a RAID 1 setup and use it to backup all of my data. Photos, Music (and movies too, but I've not really tried this) are supported and easily read by both my AppleTV and my PS3.
The Synology Forum is also pretty good - check it out for support.