Recommended Enterprise 2.0 Tools

I have tried the "Answers" feature on LinkedIn a couple of times. Last week I posted a question about personal experiences from using Enterprise 2.0 tools. This was my question:
Which products would you recommend, and why, for enterprise use
(deployable, scalable, localization support, LDAP integration, open
standardsbased API...) in the following software categories:


1. Wikis
2. Blogs
3. Social bookmarking / tagging
4. Social software / networking

I would be greatful to hear about experiences from a user perspective as well as customer cases.


I've got a few answers so far, but only one answering my question directly. One answer pointed me to this quite nice overview of Enterprise 2.0 and another to Social Media Today where I found posts like My ten favourite Enterprise 2.0 applications.

I am looking for personal experiences from using products (not SaaS) in these categories, products that have been deployed as components in an enterprise IT infrastructure. If you have personal experiences to share (or can point me to others who have), please do!