Pradyumna - 11:53 pm on Oct 10, 2006 (gmt 0) "
In my previous project I did experiment on this. We had only one topic but we experimented on creating a site on forum, blog, social networking and many other ideas. One of the biggest headake we had was the content. I seriously think What tedster has said is exactly right
You can cross-link in moderation, but it's not going to do much good until the "weight" of each domain gets rolling. It's a big-old job, and not to be taken on lightly, least you jeopardize the core domain. The days of easy index spamming and promotion through sheer numbers of backlinks are no longer with us."