Part of the reason I started this thread was because I was having trouble finding decent resources, but also because I thought it might be of benefit to others wishing to undertake the practice as well. So far, the only book I've turned up that mentions Asubha Bhavana is "The State of Mind Called Beautiful", by Sayadaw U Pandita, and since I owned the book I took a look at it and was somewhat dismayed that it only mentions it in passing. Clearly this is not a very popular topic, at least as far as books written in English are concerned. Anyway, these are the best things on the subject I've found so far:
The first is a method of contemplation which I find appealing because it's systematic like metta phrases:
and the second is a talk on the subject by Ajahn Brahm:
Anyway, if anyone knows of any books please feel free to mention them!
"The heart of the path is quite easy. There’s no need to explain anything at length. Let go of love and hate and let things be. That’s all that I do in my own practice." - Ajahn Chah