I just spotted this list of Search Commands for Google Buzz, via a Google Buzz from BuzzUsers very handy if you want to filter your stream by Source, Author or commenter.

source:xxxxx
You can use source: followed by "friendfeed", "twitter", "reader" or "buzz" to search for buzzes from a certain source. Replace "xxxxx" with the source.

author:xxxxx
You can use this to search for a certain author. Replace "xxxxx" with the author's name.

commenter:xxxxx
You can use this to search for a certain commenter. Replace "xxxxx" with the commenter's name.

has:xxxxx
You can use this to search for buzzes containing either a video, a link, or an image. Just replace xxxxx with "video", "link" or "image".

Don't forget to Friend the charity BullyingUK's Buzz Profile.