Which web apps for link building network?

If you were building your own network of websites, which web apps would you use?

So far I'm using:
- WordPress
- PHPDug
- Pligg
- Scuttle

The purpose there websites serve is to push links/content to them and to interconnect them.

Also, which platforms is it worth scraping for? (again, wordpress, pligg, scuttle come to mind).
Anything else?