I have created a LTE/3G switch for Jelly Bean LTE Galaxy Nexus. It is currently only available for the LTE Nexus and does a great job at aiding the user conserve battery life.
This app also works with ICS... not that any Gnex owners haven't upgraded.
Here is a link to the app. Thanks for looking and let me know if you have any questions!
https://play.google.com/store/apps/details?id=com.adamapps.lteswitch&feature=search_r esult#?t=W251bGwsMSwyLDEsImNvbS5hZGFtYXBwcy5sdGVzd 2l0Y2giXQ..