Events at VCF do sound like a fun idea. How about....
Computer Clinic
A loose group of experts that converge on some specific table or area to
help people get their old computers working. Setup should include ability
to make boot floppies, maybe print some .pdf manual pages (or put the .pdf
on floppy).
Contest on who can find the best stuff in the seller area (based on the
antique show format, maybe even with a live auction at the end to set
value).
Live auction of computer stuff. See if you can talk a few of the local
auction houses into making a BIG combined auction.
Vintage geek clothing contest.