If you want to unsubscribe a feed in Google Reader you have to click on the Feed Settings pulldown menu and select Unsubscribe from the list. After that a confirmation dialog appears asking you if you really want to unsubscribe from that feed. If you subscribe to feed regularly or want to clean up your feeds you are in for a solid clicking frenzy.
Firefox users – and everyone else using a browser compatible with Greasemonkey – can rejoice because someone created a Unsubscribe button for Google Reader that saves the user one click and lots of mouse movement. The Unsubscribe button is added next to the two buttons Mark all as read and Refresh and a click brings up the confirmation dialog immediately.

To make this work you need to have the Greasmonkey add-on installed. The Google Reader Unsubscribe script can then be simply installed by left-clicking it.
Related posts:
- Google Reader Automatically Translates Feeds
- Google Reader ads recommended feeds
- Google Reader Essentials Userscript
- gReactions Adds Comments To Google Reader
- Configure function for double right-click
- How To Sort Feeds In Google Reader Alphabetically Again
- Google Reader Now Offering Option To Sort Alphabetically
- Sort Subscriptions Alphabetically in Google Reader

This script may be dangerous.
It appears that if you view items by tags, as I do, instead of viewing by single subscriptions, when you click the unsubscribe button, it may unsubscribe you from all of the feeds in that tag.
I’m not sure though, because I was unwilling to test that.
You don’t really want to unsubscribe from Maki DoshDosh feed, do you?