Getting people addicted to your web site

I listened to an IT-Coversations podcast from SuperNova 2006 a few days ago about games and education. The most interesting part of the podcast were the notes by Amy Jo Kim describing how games get their players addicted to them, and how those techniques could be applied to learning environments or any systems. In the social web the largest challenge usually is starting a new community. Adding the “game appeal” of the site may help.
The main appeal-increasing features seen in games and many social software applications as well are:

1. Collecting stuff: Items in WoW, links in del.icio.us, connections in LinkedId, furniture in Habbo Hotel… Allowing users to collect various things into their virtual environment will appeal to many collector-minded people, and will increase their tendency to continue using the system.
2. Earning points: The old wisdom is that any visible meter becomes a goal to people, so it is important to carefully design those meters. Earning points can be based on some rules in the system (WoW experience levels), or they can be social in nature (LinkedIn recommendations, Ebay ratings).
3. Feedback: Feedback on the progress on any meter should be provided multimodally (visual, auditive, tactile?), often, and in interesting ways. This keeps people going with the system.
4. Social exchanges: The visibility of the community and people is important. It is also important to allow the community members to communicate. Exchanging any kind of communications or tokens (blog comments, eBay ratings, Habbo Hotel presents, WoW chats) is essential for a community to flourish.
5. Customization: Making the environment look like you want is an important way to add a feeling of ownership to the user. Customization of the user interface is an easy way of doing that. Also customizing your character (WoW avatar, community profile) and tailoring how things work and optimizing the things you see are also important affordances.
6. Allow for emergence: Do not overdesign the system and force people to work in a certain way. Most communities will surprise the original designers of the system. So make the system open enough to allow emerging behaviour, and be ready to modify your system to better support these emerging patterns.