Hi everyone,
I've had a bit of a scout around, but can't seem to find a solution to this problem anywhere.

I've got an 80GB iPod (Rockboxed, so it can be treated as any USB mass storage device). So far, I've been using Grsync to copy across my desktop music folder to my player, however the dreaded day has come when my music collection exceeds the capacity of the player. Is there a way to just sync the newest files, or, by some sort of process, set a selection criteria to allow my iPod to be filled with music, but for my desktop collection to continue to grow?

TL;DR- Is there a way to automate the selection of a set size of files, and synchronise them to a mass storage device, with the selection process being user-definable?

Surely I'm not the first person to have this issue, and I'm sure there are a myriad of solutions about.

Thanks in advance for your help,