This is very handy -- I've spent much of the weekend messing about with this plugin and the Overdrive plugin.
Here's my contribution; this URL leverages Google's inurl operator and BtnI syntax to go directly to the
series page on Goodreads. (I find this handy when I'm doing fixups of the series indexing, or identifying gaps.)
Code:
http://www.google.com/search?btnI=I%27m+Feeling+Lucky&q={series}+inurl:".com%2Fseries%2F"+site:goodreads.com
It's worth mention that the I'm Feeling Lucky button isn't perfect, so though you will always get a series, you may get something unexpected. (For example, if the series doesn't exist at Goodreads.) If you prefer a search that shows you the Google results, the below works. (I just have both confiigured, and use the "lucky" one first).
Code:
http://www.google.com/search?q={series}+inurl:".com%2Fseries%2F"+site:goodreads.com