1. Pretending users don't belong to other networks. If you sold breakfast cereal, would you believe that your customers would just walk into a store, buy your cereal and walk out? Of course not. People belong to multiple networks and yours is just one of them. If you really want to stand out, offer them a way to integrate their experience and take a page from online retail. When I hit Target.com - I can log in with my Amazon.com username and password. If they can use the same data, so can you.

2. Creating custom email messages and inboxes. Just about every social network does this. When I get a message in Facebook, I get a useless link that tells me I have a message. To read it, I need to click on the link. We are all used to email. Just figure out a way to send us an email with the details when something happens. When someone comments on a blog post, I get an email from Typepad with the full comment. That's useful. Having to access ten sites every day to pick up custom messages isn't.

3. Forgetting about basic usability. Many social networks do many things, and they are usually designed for many uses. Basic usability is the one thing that gets left behind. MySpace has the most confusing navigation and design since dotcom retail sites in 2000. Facebook has secret links that are impossible to navigate to (like when you have friend requests and you are logged in and can't find where to accept them). Ning.com lets you join lots of networks, but I haven't yet found a way to easily navigate back and forth between the many networks I belong to. These are common tasks and users are having trouble with them. To improve, social networks should take a page from online retail sites and learn how to rework their interface for the key calls to action. If that's too hard, just sit and watch 2-3 relatively new users struggle to navigate their way through your site. You'll get a list of issues to fix out of that, I promise.

4. Forcing unnecessary data collection. When first joining a social network, there is nothing worse than being forced to fill out an endless form with all sorts of data that they don't need and you don't want to give. Just ask me for a username, password and email (ok, and age if you're afraid teenagers might infiltrate your network). The rest can come later, if I actually like and start using your network.