I don't have an answer per se, but I am trying to work one out myself so I thought I'd chip in.
I need read-only api-style access too. I used Firebug to see where the data comes from, and it looks like there's actually a perfect data source already -- if I could get the json from the 'current' action in the board controller back, that would give me everything I need.
I'm trying to do it using a WebClient request in .NET, but I'm getting the empty board HMTL, not the JSON. If I browse directly to the /board/name/board-id/current path I get the same thing. I can't see what's different about the AJAX-ified request that causes it to return JSON.
Is there something I'm missing? This is roughly what I'm doing:
byte data = null;
using (WebClient client = new WebClient())
client.Headers["Cookie"] = "entire-cookie-string-copied-from-firebug-headers, including Token=...";
client.Headers["User-Agent"] = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1";
client.Headers["Referer"] = "https://trello.com/board/test/4e8ecf9bec9da200008a733a";
client.Headers["Host"] = "trello.com";
client.Headers["Accept"] = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
client.Headers["Accept-Charset"] = "ISO-8859-1,utf-8;q=0.7,*;q=0.7";
client.Headers["Cache-Control"] = "max-age=0";
data = client.DownloadData("https://trello.com/board/test/4e8ecf9bec9da200008a733a/current");
If somebody could help me get this working, I'm sure it'd be a good substitute for a read-only API until one is ready?
Right now, the alternative for me is writing a chrome extension and leaving it open on a headless machine or some such.