Learning to Count Cards?

[blutarski]

I'm starting to teach myself to count cards, more as a mental exercise than anything else. Anyone have any success with this? It seems you need to have an almost preternatural focus to keep an accurate count. I guess I'm asking whether this is something that's attainable by the masses, or a skill beyond most people.

Also, what keeps people from taking a bunch of cash from the online sites, where I'm sure you some nerd could fashion counting software relatively easily.