##Simply annoying Tweets
Annoyingly extended words (4+ of the same letter in a phrase): OOOOHHHHMMMMYYYYGGGGOOOODDDD
([a-z])/1{4}
Tweet w/ just a single hashtag: #omgthissucks
^ *#[^ ]+$
Not a regex, but self retweets: In case you missed it I pooped this morning :)
In case you missed it
##App Location Updates
Path app location updates: (at Location) - path.com/foo
(at [^ ]+/) — http://[^ ]+$
Foursquare app location updates: w/ @twittername 4sq.com/foo
w/ @[^@]+http://[^ ]+$
More Foursquare app location updates: w/ 8 others 4sq.com/foo
w/+[^#]+others http://[^ ]+$
you can mute the foursquare client, no need to use regexps for foursquare