RoR apps that act as web user agents?

I'd like to find some examples of Rails apps that act as web
"user agents" (i.e., "portals" to the web at large). That is,
programs that pass requests up and content back down, but
also add some local intelligence, etc. Any suggestions?

-r

P.S. CritLink (http://zesty.ca/crit/) is an example of
      this sort of application.

Rich Morin wrote:

I'd like to find some examples of Rails apps that act as web
"user agents" (i.e., "portals" to the web at large). That is,
programs that pass requests up and content back down, but
also add some local intelligence, etc. Any suggestions?

-r

P.S. CritLink (http://zesty.ca/crit/) is an example of
      this sort of application.

Big in Japan has apps like that involving RSS:

http://www.biggu.com/projects