I planned on making this huge batch, but I suddenly lost motivation, so I'll just post what I have. These are from episodes 19 and 20, and two icons in particular contain a spoiler.
Absolutely NO credit is needed for any of these. Feel free to take, use, customize, whatever. For very simple customization, I recommend adding a 1-px black border (if you would prefer me to do it, drop me a note). Original images can be found at [http://www.firebender.com/].