1. re:Sync.
As someone has already mentioned, the Slimp3 has a mechanism for doing this already. The only way i got close to syncing the Rio's at present was when i was using my home shoutcast server, once both Rio's were on the this station, i would kill the shoutcast server and after a few seconds, restart it. You can then see the streams being re-connected in the shoutcast log and maybe 30% of the time they would be close enough to be perceived as in sync. I never tested it for any long durations though.

2. Re:VFD

I think the prices are a good bit less than $100, but i think its the server PC that would need to interface to it and not the clients. I'm thinking along the lines of the VFD acting as a general purpose display in a room.

bill