Due to a friend of mine getting mugged and injured by a knife wielding A-hole, I now carry a collapsible baton. It is 7" when collapsed and 16" when extended. The reason I don't carry pepper spray is that it is almost always windy here and I don't care to get a face full of that stuff. ASP and Monadnock make the best, but serviceable batons can be bought for less.

http://www.batondefense.com/asp-tactical-baton.html