Script Summary: For iHeartRadio: Scrobbling and loving on last.fm.
Version: 1.2.0 (BCS-1.0.2)
License: FreeBSD License (see source code). Portions dual-licensed under the MIT (Expat) License and GPLv2.
You should see a button beneath the radio's name that says either "Enable Scrobbling" or "Waiting for Token." If it says "Waiting for Token," it should say "Enable Scrobbling" shortly. If it doesn't, either Last.fm is down, or the script can't connect to last.fm for some reason (maybe some setting on your computer, or maybe your running the script in Opera without installing the other scripts).
Click allow access on the page that pops up. Go back to iHeartRadio. The button should say "Disable Scrobbling". At this point, you're set and ready to scrobble songs. (If it says "Loading...", try waiting a few seconds.)
NB: Unlike my other scripts, clicking on the Disable Scrobbling button doesn't remove the authorization. That is, you can click Enable Scrobbling again and not have to re-enable access from Last.fm. (You can only remove authorization through the browser's configuration.) If enough people (say, 10) dislike this behavior, I'll change it back (so let me know what you think).
This script is heavily based on the Bandcamp, Soundcloud, and (now-defunct) Grooveshark scrooblers. This script should also work on Chrome and Opera, though you might need additional steps to get it working on Opera.
Version 1.2.0: iHeartRadio changed their variables.
Version 1.1.1: Fixed script after iHeartRadio changed their layout.
Version 0.1.4: Lots of bugfixes.
Version 0.1.2: Fixed so buttons work on "iHeartRadio Original" stations.
Version 0.1.1: Fixed so the last.fm-related buttons work.
April 29, 2012: Initial Upload. I didn't test it after changing the code a little, so the enable scrobbling buttons didn't even work.