I can't speak for every airline, country or airport. However, the web has pretty much taken over that segment of travel. You will find a better deal surfing I think than camping out.
There are LOTS of last minute travel sites:
www.site59.com
www.go-today.com
www.cheaptickets.com
...plus, I think there is one called Lastminutetravel.com.
You can also sign on for an e-mail newsletter from each airline and they'll send you their last minute specials on a weekly or even more frequent basis...
worldwidemike