Site stats are indeed a very useful marketing resource and are key to success!
iPODs are high demand, but don't just look at the units themselves. Take another spin on it and look at the accessories market. It follows that this will be high-demand too.
I use TradeMe New Zealand to see what the peak viewing time is by day/hour to ensure I get the highest possible hit-rate for my items.
Try and think of ways to separate your listings from the 'crowd'. Play on words; additional photos; accurate and honest desription of what is for sale; and condition - if mint and new, state this. It can make all the difference.
I have used auction sites for a few years and noticed that 'full' descriptions with a few photos gain far more exposure than a one-liner without pictures.