This is the node/coffescript i was using to pull data from the forum and create a csv. You need to disable cookies in browser to get an up to date session id you can use. If you want to do it regularly you probably should change the url to sort by date of registration and always just poll the last page or something like that.
async = require "async"
cheerio = require "cheerio"
parsePage = (url, target) ->
setImmediate ->
request = require("https").get url, (response) ->
filedata = ""
response.on "data", (chunk) ->
filedata += chunk
response.on "end", ->
target (cheerio.load filedata)
url = "https://bitsharestalk.org/index.php?PHPSESSID=b330a0f58442be2a1e469f4436e&action=mlist;sort=real_name;start="
dates = []
async.timesSeries 195, (id, cb) ->
parsePage url+(id*30), ($) ->
$("tr td:nth-child(7)").each (i, v) ->
dates.push new Date($(v).text()) / 1000
cb()
, ->
max = 0
dates.forEach (date) ->
max = i if i > max
regByDay = {}
days = dates.map (i) ->
Math.floor (max-i)/84600
days.forEach (day) ->
regByDay[day] = 0 unless regByDay[day]
regByDay[day]++
list = ""
for k of regByDay
list += k + ";" + regByDay[k] + "\n"
console.log list