class Typeblogs(models.Model):
    ...
class Myblogs(models.Model):
    typeblog = models.ForeignKey(Typeblogs, verbose_name = u'Тип')

        'cat_id' : Typeblogs.objects.select_related().get(id=id),
        'myblogs' : cat_id.myblogs_set.all(),

        'cat_id' : Typeblogs.objects.select_related().get(id=id),
        'myblogs' : cat_id.typeblogs_myblogs.all(),

from django.template import RequestContext
from django.shortcuts import render_to_response
from myblogs.models import *
def cat_id(request, id):
    return render_to_response("myblogs/myblogs.html",
    {
        'cat':Typeblogs.objects.select_related().filter(show=True),
        'cat_id' : Typeblogs.objects.select_related().get(id=id),
        'myblogs' : cat_id.myblogs_set.all(),
    }, context_instance=RequestContext(request))

        'myblogs':Myblogs.objects.filter(show=True,typeblog=id),

 'myblogs' : cat_id.myblogs_set.all(),