proj
  --proj/celery.py

from __future__ import absolute_import

import os

from celery import Celery

from django.conf import settings

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'proj.settings')

app = Celery('proj')

# Using a string here means the worker will not have to
# pickle the object when using Windows.
app.config_from_object('django.conf:settings')
app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

@app.task(bind=True)
def debug_task(self):
    print('Request:{0!r}'.format(self.request))

proj
 ---proj/celery.py
 ---app/tasks.py

from __future__ import absolute_import

from celery.decorators import task

@task()
def user_send_activation_email(user):
    user.send_activation_email()

from django.shortcuts import render_to_response, redirect,render
from django.conf import settings
from django.http import HttpResponse,HttpResponseRedirect,Http404
from django.template import RequestContext
from app.accounts.forms import SignupForm
from django.contrib.auth import get_user_model
from app.sns_utils import generate_sha1
from app.tasks import user_send_activation_email

def signup(request):
    if request.method=='POST':
        form=SignupForm(data=request.POST)
        if form.is_valid():
            UserModel=get_user_model()
            username = form.cleaned_data['username']
            email = form.cleaned_data['email']
            password = form.cleaned_data['password']
             user=UserModel.objects.create_user(username=username,email=email,password=password)
            user.activation_key = generate_sha1(username)
            user.save()
            user_send_activation_email.delay(user=user)


            return redirect('/')

BROKER_URL = 'amqp://guest:guest@localhost:5672//'

CELERY_RESULT_BACKEND = 'amqp://guest:guest@localhost:5672//'

CELERY_TASK_SERIALIZER = 'json'

EncodeError at /accounts/signup/
<MyUser: vmuser630> is not JSON serializable
Request Method: POST
Request URL:    http://localhost:8000/accounts/signup/
Django Version: 1.6
Exception Type: EncodeError
Exception Value:
<MyUser: vmuser630> is not JSON serializable
Exception Location: C:Python33libjsonencoder.py in default, line 173
Python Executable:  C:Python33python.exe
Python Version: 3.3.2

CELERY_TASK_SERIALIZER = 'json'

user.send_activation_email()

from __future__ import absolute_import

from celery.decorators import task
from django.contrib.auth import get_user_model

@task()
def user_send_activation_email(user_id):
    user = get_user_model().objects.get(pk=user_id)
    user.send_activation_email()

user_send_activation_email.delay(user_id=user.pk)