I also self-spank. 
Like most of you, I never manage to get the sting to last very long tho ( 
I have a variety of implements that I use including a wooden bath brush (that packs some punch!)and a hard sandal. 
I bought myself a new implement today...an oversized wooden spoon!! Haven't used it yet, but it looks pretty damn powerful, with the handle plenty long enough to get a good swing on it! 
For those of you in UK, I got it in BHS (in the xmas section no less!!) 
Looking forward to using that!