WordPress MU

Hi !
Sorry for the post title but i don't find my words.
I'm looking for a way to retrieve (find?) all RSS feed existing from my wpmu intall with an action that is specified. So rss will looks like: http://*.mywpmuinstall.com/index.php?rss=true&action=thename

Some of the blogs on my install could probably don't have this category.

Any advice could be great !

Thanks !!

My idea is that i maybe should parse a RSS of the entire website, and filter them...

If someone has a better idea, tell me ! ;)

Donncha's sitewide tags plugin. It stuffs copies of all entries into one tags blog, thus creating a separate feed for every single tag.

Ok thank you andrea. I'm going to take a look at it!