Amiga-Hardware.com identifies them as Time-Based Correctors (TBCs), and I gather they're for fixing the incomming video signal's timing so that it works with the Toaster.
yep
The one that worries me is a rather cool looking card, called The Kitchen Sync.
this is a time base corrector card too (i think it has two TBCs in it) and the plug(s) are probably for the hardware remote controller, which i guess you don't have.
