Well that's a new one on me, and I had to hit Google to find what a Smartboard is:
http://en.wikipedia.org/wiki/Smartboard
But you mention Wacom, and AFAIK they don't make Smartboards according to the above definition, but rather what have always referred to as Graphics Tablets. If that's what you are after, then it depends on your budget, but the Intuos tablets seem to be favourite (although I think Wacom have changed the name now — why on earth does it have to be so complicated?
I use a medium Intuos 4, but if I was shopping today, I'd chose the Intuos 5 Touch. I'd like some sort of Cintiq, or the Companion, but the Cintiqs are too big to fit into my desktop and workflow, and the Companion is way too expensive for a souped up iPad thingie.
If you already have an iPad, take a look at the Adobe Ink & Slide (Pen & Ruler in English) Has anyone got one of these yet?