The icon should follow Apples Human Interface Guidelines (HIG) (http://developer.apple.com/iphone/l…mages.html)
I will need versions of the icon at
114x114 (iPhone 4)
512x512 (App Store)
I generally like icons with a 3-D look, that have depth, texture and are modern looking (since this whole environment is the latest in mobile technology). Check out Tap Tap Tap for a company that I think is a real class act, from website to software.
If you load iTunes and look at What's Hot, you'll see some good examples. Some of my favourites include
"NotifyMe 2", "Flight Control", and "Expenditure" -- the best way to find them is through a keyword search.
Please just ask if you have any questions.
PS -- Also check out iZenDev.com, the little guy that is the logo might be a good starting point...