Blogpool is a project mainly written in Java, it's free.
BlogPool
BlogPool
Human posts a blog entry
Blog pings one or more BlogPool services
BlogPool services respond with feedback as public comments or private message
Discarded responses indicate negative feedback to the service
Published responses indicate positive feedback
A variety of services and multi-services; ranging from simple to complex
Most “helpful” services self-advertise
http://automenta.com/blogpool