I think it would be a good idea to have a standard transliteration protocol for writing Arabic terms in English. In one of the answers below, someone can add a table or list of transliteration symbols with corresponding Arabic letters. For example, I prefer saying arkān over arkaan.
I would propose basing our system on the one that's been developed for Wikipedia here.
The Basic Transcription rules (e.g., arkan instead of either arkān or arkaan) should be sufficient for most purposes. If an exact reading is required for something it would probably be better to just quote the Arabic text itself.
Having to learn a standard transliteration scheme would be a major barrier to anybody trying to answer questions here. This is something that I had to come around to myself; however, I have been convinced that consistency in transliteration isn't really worth that much. It does make searching the site somewhat easier, but since I don't think it's reasonable to expect that every single post will follow the convention, it's not like it really completely solves that problem anyway. Google is probably a better way of searching the site in any case.