Well, besides the first three Ecumenical Councils, I think that each church within OO has developed their own system of Canons regarding its own needs. I can point you to a few resources, but at least in the Armenian tradition, this would be considered a highly scholarly pursuit in that published materials are not really available to the general public as far as I know. Not only would you have to know Armenian, but you would probably have to go to Armenia itself to even find the resources.
I suspect that this is the case not just for the Armenians, but for all the OO Churches.
For the West Syriac tradition, you can consult a work by Arthur Voobus titled The Synodicon in the West Syrian Tradition
; this contains the text of the canons used by our Church in Syriac (vol. 1) and in English translation (vol. 2). Much of this is simply the Corpus Antiochenum
, plus subsequent "local" legislation. I don't think you can find this work online, but much of the contents can be found online, for instance, if you search for the individual collections of canons which make up the CA (you could probably arrange to borrow Voobus' work through inter-library loan).
Bar Ebroyo collected much of this type of material and put it together in an anthology called the Nomocanon
, with a sort of "Cliff Notes" summary called Hudoyo
. Neither exists in English as far as I know, though that could've changed. When I had to consult Bar Ebroyo's Nomocanon
for my thesis, I had to borrow copies from a fellow student from Aleppo and read it in Syriac. Hudoyo
is available in Syriac, of course, but also in French and Malayalam. Have fun with that...I sure did!
It should be noted that these are basically collections of canons, which the bishops apply based on the given situation (past precedent also plays its part); it's not a "Code of Canon Law" like you see, for instance, in the Roman Catholic Church.
Though it's technically different, Churches sometimes use their own internal "Constitutions" or "Charters" or some similar documents to govern day to day business. Some of these are available online in English:
Syriac Orthodox Church of Antiochhttp://www.soc-wus.org/ourchurch/constitution.htm
Malankara Orthodox Syrian Churchhttp://mosc.in/images/stories/File/MalankaraSabha/The%20Constitution.pdf Edited to fix tags.