What is a bookmarklet, first of all? From Wikipedia:

"A bookmarklet is a small JavaScript program that can be stored as a URL within a bookmark in most popular web browsers, or within hyperlinks on a web page. Because Internet Explorer uses the term favorites instead of bookmarks, bookmarklets are also less commonly called favlets or favelets."

Okay, now that we all know what they are, I found this neato Google Reader bookmarklet via Steve Rubel; it allows you to "subscribe to any RSS-enabled site you're visiting" without having to switch back and forth to Google Reader.

Related: RSS Defined: RSS, short for Really Simple Syndication, is revolutionizing the way we search for content.