Depending on how violent the local "thugs" are in your neighborhood I would just carry something like a taser. Non-lethal and I can tell you from experience that it does NOT fell good to get a jolt from one.
http://www.personalarms.com/tasers.htm
^^^ thats what I got hit with.
I have also gotten sprayed with pepper spray and it was very affective.
http://www.peppersprayinc.com/mace_triple_action.htm
^^^pepper spray infused with CN tear gas. Seems like nasty stuff.