Found this great article by Guy Kawasaki on entrepreneur.com. Lots of great tips and ideas.
Here's Guy's list of what NOT to do:
Forcing immediate registration: Requiring a new user to register is a reasonable request—after you've sucked him in. The sites that require registration as the first step are putting a barrier in front of adoption.
The long URL: Say a site generates a URL that's 70 characters long or more. When you copy, paste and e-mail this URL, a line break is added. Then, people can't click on the link or it only links to the first part of the URL.
Windows that don't generate URLs: Have you ever wanted to point people to a page, but the page has no URL? Did the company decide it didn't want referrals, links and additional traffic?
The unsearchable website: Some sites don't offer a search option. If your site goes deeper than one level, it needs a search box.
Sites without Delicious, Digg and Fark bookmarks: There's no reason why a company wouldn't want its fans to bookmark its pages. When my blog hits the front page of Digg, page views typically increase six or seven times.
Limiting contact to e-mail: Don't get me wrong; I live and die by e-mail. But sometimes I want to call or even snail-mail a company. Many companies only let you send an e-mail via their "Contact Us" page. Why can't companies be honest and just call it "Don't Contact Us"?
Lack of feeds and e-mail lists: Make getting information about your products and services easy by providing e-mail and RSS feeds for content and PR newsletters.
Making users retype e-mail addresses: How about the patent-pending, curve-jumping Web 2.0 company that wants you to share content but requires you to retype your friends' e-mail addresses? I have 7,703 e-mail addresses in Microsoft Entourage. I'm not going to retype them into some done-as-an-afterthought address book.
No e-mail addresses as usernames: I'm a member of hundreds of sites. I can't remember my usernames, but I can remember my e-mail address. So why not let me use that?
Case-sensitive usernames and passwords: I know; these are more secure. But then I'm more likely to type in my user name and password incorrectly.
Friction-full commenting: "Moderated comments" is an oxymoron. If your company is trying to be a hip, myth-busting, hypocrisy-outing joint, it should let anyone comment. Also, many times I've started to leave a comment on a blog but stopped when I realized I'd have to register.
Unreadable confirmation codes: A visual confirmation graphic system is a good thing, but many are too difficult to read. All you have to prove is that you're not a robot. So if the code is "ghj1lK," entering "ghj11K" should be good enough.
E-mails without signatures: Communication would be so much easier if everyone included a complete e-mail signature with their name, company, address, phone and e-mail address.
