What's a good site for online penny auctions and why?

There's really no "good" penny auction sites because you have to prepay for your bids (generally in lots of 10 or more) @ roughly $0.60 / bid FOR A CHANCE at getting an item for a heavily discounted price (because somebody else could outbid you before it closes).

The main reason why those sites can sell stuff like an iPad for $20.00 is that they made roughly $1,200.00 (2000 bids @ $0.60 / bid -- again, each bid increases the price by $0.01) on all the bids from the auction... so the site is making a crapload of money in the process, even if you never win any of those auctions.

While this isn't the answer you want to hear, I hope this sheds some light (albeit, an unflattering one) on the subject.

You can find the best sites by going to the penny auction data mining company http://www.allpennyauctions.com/ There are user reviews of every site and a list of sites with free bids. That way you know what you're getting into in advance.

The main objective of the penny auction site is to sell bids and not to sell items. probably some of there employees are bidding in the auction to prolong the bidding time and to earn more income.

So don't fall on them.