Get together a pool of some inexpensive Vintage staples that cover several deck archetypes, cards like Foundry Inspector, Phyrexian Revoker, Flame-Kin Zealot, Ichorid, Brainstorm, Ponder, Dark ritual. Make sure you have one card for everyone in attendance and have everyone sign them at some point throughout the event, you can also put the date and location or name of the event on the cards as well. At the end of the event you can draft the signed cards in whatever order you choose, usually starting from the bottom of the standings and working up is good as the people at the top likely already got some form of prize from the event. Everybody gets a group-signed Vintage playable card and has good way to remember the day. It was something we started doing at our Old School events but could very easily be done at any event for any format!
Here's a picture of the Mind's Desire I got from the last Vintage event we ran in Chicago.