Most of the online auctions I've seen were a scam. Like Quibids for one. I think the closest to an auction and a fairly reliable one would be eBay. The rest I've seen aren't too great.
Online auctioning could certainly be seen as an exciting way of shopping in many respects. What is most enticing about it is that you are competing with other buyers within a restricted time frame, and if you enjoy the thrill of 'winning', this is exactly what you stand to gain from it.
Human psychology tells us something is most attractive when it is unavailable. That is why a lot of companies cleverly market their sales within a specific time frame which excites the buyer into wanting to grab something that is in some way difficult to have or find. Once the sales are over, they feel privileged to have purchased something for a cheaper price than they might have had to pay, or something that was scarce and in demand.
This is the same principle behind auctioning, there may be only one item, and many people are wanting to purchase this item, so winning it gives you that feeling of satisfaction and privilege.