I recently came across a talk from the end of 2006 by Jyri Engstrom (the founder of Jaiku) about "Growing networks around social objects" (Bokardo with the tip off). I really like the language Jyri uses to talk about the social web.  His post about object centered sociality is wonderful. The following points and paraphrases are from a talk Jyri gave at Microsoft.

Growing Networks around social objects by Jyri Engstrom

1. Define your object

how can people act on the object

2. Define your verbs

peramalink objects
embeds/widgets to make users objects portable
share actual files

4. Turn invitations into gifts

paypal sign up a friend $10 bonus
skype sign up friend for free calls

5.  charge the publishers not the spectators

"freemium business model"

This post is part 2 of a series that collects peoples thoughts on designing and building communities on the social web. Part 1, Part 2. I collect the key concepts from the series in a mindmap on mindmesiter (Click and drag to move around).