Anyone applied Heisig's method to anything other than RTK itself? For example zhongwen.com.

I don't really understand what you mean. Heisigs method has to do with creating stories about radicals, I don't see how it could be used in other situations than kanji, hanzi and other similar writing styles.

I'm sure using visual memory is a common part of other techniques if that's what you mean.

Khatzumoto of AJATT fame mentions using the Heisig method with zhongwen in one of the comments accompanying this post

khatzumoto Wrote:I originally learned kanji with the intention of using them for Chinese first, applying the Heisig method to http://www.zhongwen.com

Classical Tibetan sanscript. It has a rather complicated alphabet that builds upon itself like kanji. There are only about 1000 words used in all the major Dharma Pujas in Tibetan Buddhism practice so I would need to create 1000 stories.

My profile pick is of the Tibetan letter AH. It looks like a 13V~olt battery to me. It is used in Tantric practice to purify speech and also pacify lust. So it has a red color. When a woman uses a "toy" to satisfy lust, maybe she has a 13Volt battery in it. Perhaps she also moans, AHHH

Heisig's method is usable with the kana, so I don't see why it wouldn't be usable with the Korean characters, for instance.

I mean, using a source of kanji other than the jouyou list arranged in his order.