Update: In an email conversation Ionut Alex Chitu suggested a better way to do it. It is by using this url : http://www.google.com/reader/public/subscriptions/user/-/label/FOLDER where Folder is the name of folder you are trying to export. He has further written an elaborate blog post on it.
Let’s say you love reading blogs related to different subjects and subscribe to a lot of feeds in your Google Reader. You’ve organized the feeds under different folders and tags representing different categories. Now your friend asks you what productivity related blogs you read and demands the specific list of feeds.
The best choice is to give the OPML file which contains the list of your productivity related feeds so that he can use it to subscribe to all of them in one click in his feed reader. But like most of the other web based RSS readers, Google Reader doesn’t support export of specific feeds. So either you give him the feed urls manually or export your subscriptions and then edit the OPML file yourself.
Editing the OPML file could be difficult and time consuming for a non-developer mind. Instead one can use this workaround to extract selected feeds from Google Reader. Unfortunately Google Reader itself isn’t much of a help here and this trick would require you to download a desktop based RSS reader like FeedDemon or RSS Bandit to your computer. Both these desktop based readers support both selective import and export of feeds. So you could just export your entire list from Google Reader and import them into one of these desktop based readers. And then you could export the required feeds and hence create the opml file which you can give to your friend.
This workaround is easy and less time consuming. Both the desktop based readers which I mentioned are free and can be downloaded and installed quickly, unless you have a very slow internet connection.
If you know of any other method which is better then I’d love to hear them. Keep in mind that I’m talking about a method which just requires clicks and not playing with codes or scripts.