This Pipe filters your twitter feed by either 1) tweet source, 2) a partial link URL in the tweet, or 3) a wild card character (or string) you can use to designate a tweet for SlimTwitter.
I use it to import only a select set of tweets to Tumblr.
Ignore the warning at the bottom that says all fields must be entered. The only mandatory fields are #1 and at least one of other 3. You can use all three filters at once.
Clone and edit the Pipe to add more than one value for any given category or to exclude (rather than include) tweets that match a certain category.
Pipe Web Address: http://pipes.yahoo.com/pipes/pipe.info?_id=944005725d83293c806b186b3a52c5f9