A python script, meant to run on iOS via Pythonista and from Workflow, to get a list of all of the Trello cards assigned to you with the provided app key and token, as well as the provided board ID and username.

Pythonista-Trello-Tasks.py

# coding: utf-8
# Workflow script available here: http://bit.ly/1PEvd1S

import platform

if platform.system() == 'Darwin':
    if platform.machine().startswith('iP'):
        import console
        import clipboard
        import webbrowser

import urllib2
import urllib
import json
import sys

clArgs = sys.argv[1].split(',')
appKey = clArgs[0]
appToken = clArgs[1]
boardId = clArgs[2]
userName = clArgs[3]

MyCards = []

args = { 'key': appKey,
    'token': appToken,
    'filter': 'open'}

lists_url = "https://api.trello.com/1/boards/%s/lists?%s" % (boardId, urllib.urlencode(args))

try:
    data = urllib2.urlopen(lists_url)
except urllib2.HTTPError as inst:
    raise Exception("Key or Token incorrect")

lists = json.loads(data.read())

args = {
'fields': 'all',
'key': appKey,
'token': appToken
}

for li in lists:
    cards_url = "https://api.trello.com/1/lists/%s/cards?%s" % (li['id'], urllib.urlencode(args))

    try:
        cardsdata = urllib2.urlopen(cards_url)
    except urllib2.HTTPError as inst:
        raise Exception("Key or Token incorrect")

    cards = json.loads(cardsdata.read())

    for card in cards:
        members_url = "https://api.trello.com/1/cards/%s/members?%s" % (card['id'], urllib.urlencode(args))

        try:
            membersdata = urllib2.urlopen(members_url)
        except urllib2.HTTPError as inst:
            raise Exception("Key or Token incorrect")

        members = json.loads(membersdata.read())

        for member in members:
            if member['username'] == userName:
                MyCards.append(card)
                break

newline = '\n'
MyTasks = []
for card in MyCards:
    cardNum = card['idShort']

    desc = card['desc']
    cardName = card['name']

    tasktitle = "Card #%s - %s" % (cardNum, cardName)

    MyTasks.append(tasktitle)

    if platform.system() == 'Darwin':
        if platform.machine().startswith('iP'):
            clipboard.set(newline.join(MyTasks))
webbrowser.open('workflow://')