Best I've done is on a flight from L.A. to Melbourne, Australia on United. I volunteered at check-in at SFO, and also at the Red Carpet Club in L.A. I was told they would not use me because I had checked a bag.
Boarded the flight in business class, and no sooner had I sat down than they were paging for volunteers. I was the first one at the door.
Got $600 voucher, two nights at the airport Hilton (until flight time the next night), and meal vouchers. Spent the entire next day in San Diego with a person who worked for IBM in Melbourne that also volunteered. Best part of this was the upgrade to first class the next day out, as business was full
Most recent bump was $300 voucher in early June for an oversold BWI-SFO flight. They took me by cab over to Dulles, and I arrived 2 hours later than scheduled.
[This message has been edited by tom911 (edited 07-03-2000).]