Hmm I guess the way I'd go at it would be make a simple movie that looks for a shared object that has the last count, if found use this to start counting from. If not found use a default number to start counting from and save a shared object with that number.

I've thought of several problems with thtat already as I typed it, but it should basically work.

You could perhaps do a hit counter thing that would not keep going up while on the page like the priceline example does.