[widebody911]

I can tell you what I don't like.

• "IE-only" sites; if you can't code for anything other then Internet Explorer, you shouldn't be coding
• data validation laziness: let people enter the CC info as it appears on the card; if you want to remove spaces, do so behind the scenes. Same goes for phone numbers; let people enter them in the format they've been using since Alexander Bell invented the damn thing; if your lame-ass table layout wants them a different way, you do it.
• mailing lists: don't add customers to your marketing list unless they beg you to. Just because they're buying something from you doesn't mean they want more of your crap. I buy gifts for people online, stuff that I wouldn't want in a million years, but I keep getting stupid catalogs in the mail and emails about 'specials'
• process flow: don't keep making people circle back around through the site. Have your ***** together so that if they do stray to another page on your site, they don't have to re-fill their shopping cart. I've been to some sites where if your at the 'checkout' and you decide to go back and add something to your cart, it dumps out the entire cart and you have to start over.