If you subscribe to all the blogs you found interesting at some point, you end up with a huge list of subscriptions. A possible solution is to reduce the number of items from your reading list using filters like: don't show me the posts from Google Operating System that include "YouTube" in the title. While Google Reader doesn't support filters yet, there are some tools that might help.

Google Reader Filter is a Greasemonkey script that lets you define a list of keywords you're interested in and a list of uninteresting keywords. The script highlights the posts that include your favorite keywords in the title and grays out the posts that contain keywords from the blacklist. You can use regular expressions for defining complex restrictions, like dates or long titles.


The script doesn't remove posts, so it's more like an automatic highlighter. Feed Rinse has another approach: add a feed, define a list of simple rules for filtering and you get a filtered feed that can be added to your feed reader. For some reason, I couldn't subscribe to Feed Rinse's feeds in Google Reader, even though they were valid and any other feed reader accepted them. Hopefully, it's just a temporary problem.


You could also use a Yahoo Pipe that lets you define a list of keywords that are potentially interesting. So if you enter gmail, google calendar as a filter, the pipe will obtain a list of posts that contain Gmail or Google Calendar. After running the pipe, click on "More options", select "Get as RSS" and subscribe to the feed. As Yahoo doesn't allow you to change the feed's title, you should rename it in Google Reader.

While Blogger doesn't encourage comments and communities, it's still interesting to see who comments on your blog more frequently. This information can be obtained from Blogger's comment feeds, but you need a tool for processing feeds.

Yahoo Pipes is probably the best way to combine, sort, filter and modify feeds. Inspired by this Yahoo Pipe, I created a pipe that shows the top 50 commentators from a Blogger blog, based on the most recent 5,000 comments. You can enter the URL of your blog and the number of top commentators, but the list is not generated instantaneously since Yahoo Pipe must fetch and process at most 10 GData feeds (Blogger's API doesn't include more than 500 comments in a single feed). The pipe could also be used to add the list of top commentators to the blog, using the JSON code generated by Yahoo.

Depending on the number of comments from your blog, the list may not be very meaningful. For example, if your posts get an average of 500 comments, this list will only reflect the hierarchy for the last 10 posts. To see the total number of comments from your blog, open this feed: http://BLOGNAME.blogspot.com/feeds/comments/default (replace BLOGNAME with the proper subdomain), view the page's source and search for "openSearch:totalResults". Google Operating System has 15,217 comments and the most recent 5,000 comments corresponding to the last 5 months.

Update. Here's some JavaScript code that uses Yahoo's JSON output. This could be easily added in a HTML/JavaScript page element from Blogger.


(merge the last two lines and replace BLOGNAME with your blog's subdomain name).

Tony Hirst found a simple way to place the events from a Google Calendar on a map. Assuming that the calendar is public, all you need to do is to find the XML address of the calendar, enter the address in a Yahoo Pipe that extracts the locations and generates a geoRSS feed, click on "More options" and copy the link to the KML output. You can enter the URL in a Google Maps search box and you'll see the events on a map. The items can be saved to My Maps or embedded into a web page if you select "Link to this page".

Tony notes that "the call to the Yahoo Pipe sometimes times out in the map. To guarantee the map displaying the KML feed, you could always save the KML feed as a KML file, then upload it somewhere and use that URL in the Google Map search box".

YouTube has never offered too many feeds and they were usually difficult to find. The new YouTube API changed that, but the feeds are still inaccessible from the interface. This why I decided to compile a list of the most useful YouTube feeds you may want to add in your favorite feed reader:

1. Search feeds
http://gdata.youtube.com/feeds/api/videos?orderby=updated&vq=mapreduce
(replace mapreduce with your query)

2. Search in a category
http://gdata.youtube.com/feeds/api/videos/-/Film/?vq=michel%20gondry&orderby=updated
(Film is the category, while michel gondry is the query - you need to replace the space with %20. Other categories: Music, Comedy, News, Sports, Autos, Howto.)

3. The latest videos from a channel
http://gdata.youtube.com/feeds/api/users/radiohead/uploads?orderby=updated
(replace radiohead with your channel)

...or only the videos that match your keywords:
http://gdata.youtube.com/feeds/api/users/radiohead/uploads?orderby=updated&vq=jigsaw

4. Feeds for favorite videos
http://gdata.youtube.com/feeds/api/users/garyferro/favorites?orderby=updated
(replace garyferro with your favorite username)

5. Your subscriptions
This is not a feed that comes directly from YouTube, it's a Yahoo Pipe.
http://pipes.yahoo.com/pipes/pipe.run?YouTubeUsername=google&
_id=28303b479f11e24199be4cafced31ad9&_render=rss&itemLimit=20
(concatenate the two lines and replace google with your username)

The feed above shows the latest videos from the first 25 subscriptions. For those who have more subscriptions, I created a new version of the pipe that shows the videos from up to 500 subscriptions:

http://pipes.yahoo.com/pipes/pipe.run?YouTubeUsername=MotherTalking&
_id=58e4f59f9e5e3282aaffdcbaf05ba68d&_render=rss&itemLimit=50
(concatenate the two lines and replace MotherTalking with your username)

6. Playlists
http://gdata.youtube.com/feeds/api/playlists/50653251EDB4E764
(the code in italic can be obtained from the playlists's URL (e.g.: Eric Speaks)

Yahoo Pipes is "a hosted service that lets you remix feeds and create new data mashups in a visual programming environment". In Unix, a pipe (or a pipeline) is "a set of processes chained by their standard streams, so that the output of each process feeds directly as input of the next one".

Yahoo created a service that lets you treat feeds like some standard text files.

How to create a pipe

You'll have to go to this page, sign in to Yahoo, and use a visual environment that accepts drag and drop. You'll see a small list of modules (or commands) that can be dragged to the canvas.


In this example, someone aggregated the feeds from Technorati, Google News, Yahoo News and more. The first box accepts a user query that's used for building the URL of the feeds. You'll have to use a URLBuilder for each news source and connect it to Fetch, that actually reads the content and builds one feed. To improve the output, the author sorted the feed items by publication date and removed duplicates.

As Yahoo explains, "each module has one or more terminals, represented by small circles in the interface. You can wire modules together by clicking on one module's output terminal and another module's input terminal. Now the output from the first module will serve as input to the second module."

Yahoo exports the results of a pipe in one of these formats: RSS, RDF, JSON and Atom, so it's easy to use in a web application later.

What can you do?

You can count the number of items from a feed, sort them, filter the items that match a rule, remove duplicates, extract location names and important keywords or merge two feeds.

Start by opening pre-defined pipes and understand their meaning. Then you can build your own pipe by simply cloning an existing one and adapting to your needs.

Yahoo Pipes is a very interesting example of how easy is to play with data and build useful things by simply mashing data.