# template - assumes an object "all_cats" containing all categories 
# or site sections you want to appear in the select list. 
# Probably best to put the guts of the select loop all on one line.

<form action="" method="post">
   Select another category:
   <select name="type">
       {% for cat in all_cats  %}
            <option value="{{ cat.slug }}" 
            {% ifequal cat.slug category.slug %}
            selected="selected"{% endifequal %}
            >{{ cat.title }}
       {% endfor %}
   </select> 
   <input type="submit" name="submit" value="Go" />
</form>


# views.py
# Handle the redirection.  
# Assumes a reversible URL in urls.py called events_cat that takes
# cat_slug as an arg. Season to taste.

from django.http import HttpResponseRedirect

    if request.POST.get('type'):
        return HttpResponseRedirect(reverse('events_cat', 
            kwargs={'cat_slug':request.POST['type'],}))